Holographic Pattern Generation for Head-Mounted Display (HMD) Eye Tracking Using a Diffractive Optical Element

ABSTRACT

A system for making a holographic medium for use in generating light patterns for eye tracking includes a light source configured to provide light and a beam splitter configured to separate the light into a first portion of the light and a second portion of the light that is spatially separated from the first portion of the light. The system also includes a first set of optical elements configured to transmit the first portion of the light for providing a first wide-field beam onto an optically recordable medium and one or more diffractive optical elements configured to receive the second portion of the light and project a plurality of separate light patterns onto the optically recordable medium for forming the holographic medium.

RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No. ______,entitled “Holographic In-Field Illuminator” filed concurrently herewith(Attorney Docket Number 010235-01-5202-US), U.S. patent application Ser.No. ______, entitled “Wide-Field Holographic Pattern Generation forHead-Mounted Display (HMD) Eye Tracking” filed concurrently herewith(Attorney Docket Number 010235-01-5203-US), U.S. patent application Ser.No. ______, entitled “Holographic Pattern Generation for Head-MountedDisplay (HMD) Eye Tracking Using a Lens Array” filed concurrentlyherewith (Attorney Docket Number 010235-01-5204-US), U.S. patentapplication Ser. No. ______, entitled “Holographic Pattern Generationfor Head-Mounted Display (HMD) Eye Tracking Using a Prism Array” filedconcurrently herewith (Attorney Docket Number 010235-01-5205-US), U.S.patent application Ser. No. ______, entitled “Holographic PatternGeneration for Head-Mounted Display (HMD) Eye Tracking Using an Array ofParabolic Mirrors” filed concurrently herewith (Attorney Docket Number010235-01-5206-US), and U.S. patent application Ser. No. ______,entitled “Holographic Pattern Generation for Head-Mounted Display (HMD)Eye Tracking Using a Fiber Exposure” filed concurrently herewith(Attorney Docket Number 010235-01-5208-US). All of these applicationsare incorporated by reference herein in their entireties.

TECHNICAL FIELD

This relates generally to display devices, and more specifically tohead-mounted display devices.

BACKGROUND

Head-mounted display devices (also called herein head-mounted displaysor headsets) are gaining popularity as means for providing visualinformation to a user. For example, the head-mounted display devices areused for virtual reality and augmented reality operations.

However, the size and weight of conventional head-mounted displays havelimited applications of head-mounted displays.

SUMMARY

Accordingly, there is a need for head-mounted displays that are compactand light, thereby enhancing the user's virtual-reality and/or augmentedreality experience.

In particular, conventional head-mounted display devices (e.g.,conventional head-mounted display devices configured for augmentedreality operations) project images over a large area around an eye of auser in order to provide a wide field of view in all gaze-directions(e.g., in order to deal with pupil steering). However, projecting imagesover a large area leads to reduced brightness of the projected images.Compensating for the reduced brightness typically requires a highintensity light source, which is typically large and heavy, and has highpower consumption. There is a need for eye-tracking systems fordetermining a position of a pupil of an eye in order to project imagesover a reduced area toward the pupil of the eye. Such system, in turn,allows compact, light, and low power-consumption head-mounted displays.In addition, in some cases, the content displayed by the head-mounteddisplays needs to be updated based on a gaze direction of a user, whichalso requires eye-tracking systems for determining the position of thepupil of the eye.

One approach to track movements of an eye is to illuminate a surface ofthe eye, and detect reflections of the illuminated patterns off thesurface of the eye (e.g., glints). In order to avoid occluding afield-of-view of a user, the light source for illuminating the surfaceof the eye is typically positioned away from the field-of view. However,eye tracking with such illumination has challenges, such as having totake into account a variety of eye reliefs, eye lid occlusions, irissizes and inter pupillary distances of different users. Therefore, thereis a need for eye-tracking systems with in-field (e.g.,in-field-of-view) illumination without occluding the field-of-view.

The above deficiencies and other problems associated with conventionaleye-tracking systems are reduced or eliminated by the disclosed systemswith in-field illumination of the eye.

In accordance with some embodiments, an eye-tracking system includes aholographic illuminator that includes a light source configured toprovide light and a holographic medium optically coupled with the lightsource. The holographic medium is configured to receive the lightprovided from the light source and project a plurality of separate lightpatterns concurrently toward an eye. The eye-tracking system alsoincludes a detector configured to detect a reflection of at least asubset of the plurality of separate light patterns, reflected off theeye, for determining a location of a pupil of the eye.

In accordance with some embodiments, a head-mounted display deviceincludes one or more optical elements, one or more displays configuredto project light through or off of the one or more optical elements, andthe eye-tracking system described herein.

In accordance with some embodiments, a method for determining a locationof a pupil of an eye includes providing light with a light source;receiving, with a holographic medium optically coupled with the lightsource, the light provided by the light source; and projecting, with theholographic medium, a plurality of separate light patterns concurrentlytoward an eye. The method also includes detecting, with a detector, areflection of at least a subset of the plurality of separate lightpatterns reflected off the eye of the wearer. The method furtherincludes determining, based on the reflection of at least the subset ofthe plurality of separate light patterns reflected off the eye, alocation of a pupil of the eye.

In accordance with some embodiments, a method includes providing lightfrom a light source and separating the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light. The method also includes transmittingthe first portion of the light through a first set of optical elementsto provide a first wide-field beam, transmitting the second portion ofthe light through a second set of optical elements to provide a secondwide-field beam that is spatially separated from the first wide-fieldbeam, and transmitting the second wide-field beam through a third set ofoptical elements to provide a plurality of separate light patterns. Themethod further includes concurrently projecting the first wide-fieldbeam and the plurality of separate light patterns onto an opticallyrecordable medium to form a holographic medium.

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light. The system also includes a first set ofoptical elements configured to transmit the first portion of the lightfor providing a first wide-field beam, a second set of optical elementsconfigured to transmit the second portion of the light for providing asecond wide-field beam, and a third set of optical elements opticallycoupled with the second set of optical elements and configured totransmit the second wide-field beam for providing a plurality ofseparate light patterns onto an optically recordable medium for formingthe holographic medium.

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light. The system also includes a first set ofoptical elements configured to transmit the first portion of the lightfor providing a first wide-field beam onto an optically recordablemedium, a second set of optical elements configured to transmit thesecond portion of the light through for providing a second wide-fieldbeam, and a plurality of lenses optically coupled with the second set ofoptical elements configured to receive the second wide-field beam andproject a plurality of separate light patterns onto the opticallyrecordable medium for forming the holographic medium.

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source and separating thelight into a first portion of the light and a second portion of thelight that is spatially separated from the first portion of the light.The method also includes transmitting the first portion of the lightthrough a first set of optical elements to provide a first wide-fieldbeam, transmitting the second portion of the light through a second setof optical elements to provide a second wide-field beam that isspatially separated from the first wide-field beam onto an opticallyrecordable medium, and transmitting the second wide-field beam through aplurality of lenses to provide a plurality of separate light patterns.The method further includes concurrently projecting the first wide-fieldbeam and the plurality of separate light patterns onto the opticallyrecordable medium to form the holographic medium.

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light, and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light. The system also includes a first set ofoptical elements configured to transmit the first portion of the lightfor providing a first wide-field beam onto an optically recordablemedium, a second set of optical elements configured to transmit thesecond portion of the light for providing a second wide-field beam, anda plurality of prisms optically coupled with the second set of opticalelements and configured to receive the second wide-field beam andproject a plurality of separate light patterns onto the opticallyrecordable medium for forming the holographic medium.

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source, and separating thelight into a first portion of the light and a second portion of thelight that is spatially separated from the first portion of the light.The method also includes transmitting the first portion of the lightthrough a first set of optical elements to provide a first wide-fieldbeam, transmitting the second portion of the light through a second setof optical elements to provide a second wide-field beam that isspatially separated from the first wide-field beam onto an opticallyrecordable medium, and transmitting the second wide-field beam through aplurality of prisms to provide a plurality of separate light patterns.The method further includes concurrently projecting the first wide-fieldbeam and the plurality of separate light patterns onto the opticallyrecordable medium to form the holographic medium.

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light. The system also includes a first set ofoptical elements configured to transmit the first portion of the lightfor providing a first wide-field beam onto an optically recordablemedium, a second set of optical elements configured to transmit thesecond portion of the light for providing a second wide-field beam, anda plurality of parabolic reflectors optically coupled with the secondset of optical elements and configured to receive the second wide-fieldbeam and project a plurality of separate light patterns onto theoptically recordable medium for forming the holographic medium.

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source, and separating thelight into a first portion of the light and a second portion of thelight that is spatially separated from the first portion of the light.The method also includes transmitting the first portion of the lightthrough a first set of optical elements to provide a first wide-fieldbeam, transmitting the second portion of the light through a second setof optical elements to provide a second wide-field beam that isspatially separated from the first wide-field beam onto an opticallyrecordable medium, and reflecting the second wide-field beam with aplurality of parabolic reflectors to provide a plurality of separatelight patterns. The method further includes concurrently projecting thefirst wide-field beam and reflecting the plurality of separate lightpatterns onto the optically recordable medium to form the holographicmedium.

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light. The system also includes a first set ofoptical elements configured to transmit the first portion of the lightfor providing a first wide-field beam onto an optically recordablemedium and one or more diffractive optical elements configured toreceive the second portion of the light and project a plurality ofseparate light patterns onto the optically recordable medium for formingthe holographic medium.

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source and separating thelight into a first portion of the light and a second portion of thelight that is spatially separated from the first portion of the light.The method also includes transmitting the first portion of the lightthrough a first set of optical elements to provide a first wide-fieldbeam, transmitting the second portion of the light through one or morediffractive optical elements to provide a plurality of separate lightpatterns, and concurrently projecting the first wide-field beam and theplurality of separate light patterns onto the optically recordablemedium to form the holographic medium.

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light. The system also includes a first set ofoptical elements configured to transmit the first portion of the lightfor providing a first wide-field beam onto an optically recordablemedium and a plurality of optical fibers configured to receive thesecond portion of the light and project a plurality of separate lightpatterns onto the optically recordable medium for forming theholographic medium.

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source and separating thelight into a first portion of the light and a second portion of thelight that is spatially separated from the first portion of the light.The method also includes transmitting the first portion of the lightthrough a first set of optical elements to provide a first wide-fieldbeam, transmitting the second portion of the light through a pluralityof optical fibers to provide a plurality of separate light patterns, andconcurrently projecting the first wide-field beam and the plurality ofseparate light patterns onto the optically recordable medium to form theholographic medium.

In accordance with some embodiments, a holographic medium is made by anyof the methods described herein.

Thus, the disclosed embodiments provide eye-tracking systems andeye-tracking methods based on holographic media, and devices and methodsfor making holographic media.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the various described embodiments,reference should be made to the Description of Embodiments below, inconjunction with the following drawings in which like reference numeralsrefer to corresponding parts throughout the figures.

FIG. 1 is a perspective view of a display device in accordance with someembodiments.

FIG. 2 is a block diagram of a system including a display device inaccordance with some embodiments.

FIG. 3 is an isometric view of a display device in accordance with someembodiments.

FIG. 4A is a schematic diagram illustrating a holographic illuminator inaccordance with some embodiments.

FIG. 4B is a schematic diagram illustrating a holographic illuminator inaccordance with some embodiments.

FIG. 4C is a schematic diagram illustrating a holographic illuminator inaccordance with some embodiments.

FIG. 4D is a schematic diagram illustrating a holographic illuminatorshown in

FIG. 4A.

FIG. 4E is a schematic diagram illustrating a holographic illuminator inaccordance with some embodiments.

FIGS. 5A-5F are schematic diagrams illustrating configurations of lightpatterns used for eye tracking in accordance with some embodiments.

FIG. 6A is a schematic diagram illustrating a display device inaccordance with some embodiments.

FIG. 6B is a schematic diagram illustrating a display device inaccordance with some embodiments.

FIG. 6C is a schematic diagram illustrating a display device inaccordance with some embodiments.

FIG. 6D is a schematic diagram illustrating a display device inaccordance with some embodiments.

FIG. 7A is an image illustrating a plurality of light patterns reflectedoff one or more surfaces of an eye in accordance with some embodiments.

FIG. 7B is an image illustrating a plurality of light patterns and areflection of the plurality of light patterns from one or more surfacesof an eye in accordance with some embodiments.

FIG. 8A is a schematic diagram illustrating a system for preparing awide-field holographic medium in accordance with some embodiments.

FIG. 8B is a schematic diagram illustrating a system for preparing awide-field holographic medium in accordance with some embodiments.

FIG. 8C is a schematic diagram illustrating adjustment of a direction ofa reference beam onto an optically recordable medium for preparing awide-field holographic medium in accordance with some embodiments.

FIG. 9A is a schematic diagram illustrating a side view of opticalelements for preparing a holographic medium in accordance with someembodiments.

FIG. 9B is a schematic diagram illustrating a plan view of lenses forpreparing a holographic medium in accordance with some embodiments.

FIG. 9C is a schematic diagram illustrating a plan view of lenses forpreparing a holographic medium in accordance with some embodiments.

FIG. 9D is a schematic diagram illustrating a side view of opticalelements for preparing a holographic medium in accordance with someembodiments.

FIG. 9E is a schematic diagram illustrating a side view of opticalelements for preparing a holographic medium in accordance with someembodiments.

FIG. 9F is a schematic diagram illustrating optical elements forpreparing a holographic medium in accordance with some embodiments.

FIG. 9G is a schematic diagram illustrating a side view of opticalelements for preparing a holographic medium in accordance with someembodiments.

FIGS. 9H-9J are schematic diagrams illustrating side views of opticalelements for preparing a holographic medium in accordance with someembodiments.

FIG. 9K is a schematic diagram illustrating a side view of opticalelements for preparing a holographic medium in accordance with someembodiments.

FIG. 9L is a schematic diagram illustrating a side view of opticalelements for preparing a holographic medium in accordance with someembodiments.

These figures are not drawn to scale unless indicated otherwise.

DETAILED DESCRIPTION

Eye-tracking systems with in-field illumination provide accurate andreliable determination of a position of a pupil of an eye because theillumination is projected toward the eye in the direction of thefield-of-view of the eye. Such illumination projects glints in thecenter region of the eye, which can be analyzed for accuratedetermination of the position of the pupil of the eye. The disclosedembodiments provide (i) holographic illuminators and (ii) methods andsystems for making such holographic illuminators that provide in-fieldillumination. In addition, such holographic illuminators have reduced orno occlusion of the field-of-view of the eye of the user.

In some embodiments, the holographic illuminator includes a light sourcepositioned away from the field-of-view of an eye projecting anon-visible (e.g., an infrared (IR) or near-infrared (NIR)) light towarda holographic medium (e.g., a holographic film) positioned in-field ofthe eye.

Reference will now be made to embodiments, examples of which areillustrated in the accompanying drawings. In the following description,numerous specific details are set forth in order to provide anunderstanding of the various described embodiments. However, it will beapparent to one of ordinary skill in the art that the various describedembodiments may be practiced without these specific details. In otherinstances, well-known methods, procedures, components, circuits, andnetworks have not been described in detail so as not to unnecessarilyobscure aspects of the embodiments.

It will also be understood that, although the terms first, second, etc.are, in some instances, used herein to describe various elements, theseelements should not be limited by these terms. These terms are used onlyto distinguish one element from another. For example, a first surfacecould be termed a second surface, and, similarly, a second surface couldbe termed a first surface, without departing from the scope of thevarious described embodiments. The first surface and the second surfaceare both surfaces, but they are not the same surface.

The terminology used in the description of the various describedembodiments herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used in thedescription of the various described embodiments and the appendedclaims, the singular forms “a,” “an,” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will also be understood that the term “and/or” as usedherein refers to and encompasses any and all possible combinations ofone or more of the associated listed items. It will be furtherunderstood that the terms “includes,” “including,” “comprises,” and/or“comprising,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof. The term “exemplary” is used herein in the senseof “serving as an example, instance, or illustration” and not in thesense of “representing the best of its kind.”

FIG. 1 illustrates display device 100 in accordance with someembodiments. In some embodiments, display device 100 is configured to beworn on a head of a user (e.g., by having the form of spectacles oreyeglasses, as shown in FIG. 1) or to be included as part of a helmetthat is to be worn by the user. When display device 100 is configured tobe worn on a head of a user or to be included as part of a helmet,display device 100 is called a head-mounted display. Alternatively,display device 100 is configured for placement in proximity of an eye oreyes of the user at a fixed location, without being head-mounted (e.g.,display device 100 is mounted in a vehicle, such as a car or anairplane, for placement in front of an eye or eyes of the user). Asshown in FIG. 1, display device 100 includes display 110. Display 110 isconfigured for presenting visual contents (e.g., augmented realitycontents, virtual reality contents, mixed reality contents, or anycombination thereof) to a user.

In some embodiments, display device 100 includes one or more componentsdescribed herein with respect to FIG. 2. In some embodiments, displaydevice 100 includes additional components not shown in FIG. 2.

FIG. 2 is a block diagram of system 200 in accordance with someembodiments. The system 200 shown in FIG. 2 includes display device 205(which corresponds to display device 100 shown in FIG. 1), imagingdevice 235, and input interface 250 that are each coupled to console210. While FIG. 2 shows an example of system 200 including one displaydevice 205, imaging device 235, and input interface 250, in otherembodiments, any number of these components may be included in system200. For example, there may be multiple display devices 205 each havingassociated input interface 250 and being monitored by one or moreimaging devices 235, with each display device 205, input interface 250,and imaging devices 235 communicating with console 210. In alternativeconfigurations, different and/or additional components may be includedin system 200. For example, in some embodiments, console 210 isconnected via a network (e.g., the Internet) to system 200 or isself-contained as part of display device 205 (e.g., physically locatedinside display device 205). In some embodiments, display device 205 isused to create mixed reality by adding in a view of the realsurroundings. Thus, display device 205 and system 200 described here candeliver augmented reality, virtual reality, and mixed reality.

In some embodiments, as shown in FIG. 1, display device 205 is ahead-mounted display that presents media to a user. Examples of mediapresented by display device 205 include one or more images, video,audio, or some combination thereof. In some embodiments, audio ispresented via an external device (e.g., speakers and/or headphones) thatreceives audio information from display device 205, console 210, orboth, and presents audio data based on the audio information. In someembodiments, display device 205 immerses a user in an augmentedenvironment.

In some embodiments, display device 205 also acts as an augmentedreality (AR) headset. In these embodiments, display device 205 augmentsviews of a physical, real-world environment with computer-generatedelements (e.g., images, video, sound, etc.). Moreover, in someembodiments, display device 205 is able to cycle between different typesof operation. Thus, display device 205 operate as a virtual reality (VR)device, an augmented reality (AR) device, as glasses or some combinationthereof (e.g., glasses with no optical correction, glasses opticallycorrected for the user, sunglasses, or some combination thereof) basedon instructions from application engine 255.

Display device 205 includes electronic display 215, one or moreprocessors 216, eye tracking module 217, adjustment module 218, one ormore locators 220, one or more position sensors 225, one or moreposition cameras 222, memory 228, inertial measurement unit (IMU) 230,one or more reflective elements 260 or a subset or superset thereof(e.g., display device 205 with electronic display 215, one or moreprocessors 216, and memory 228, without any other listed components).Some embodiments of display device 205 have different modules than thosedescribed here. Similarly, the functions can be distributed among themodules in a different manner than is described here.

One or more processors 216 (e.g., processing units or cores) executeinstructions stored in memory 228. Memory 228 includes high-speed randomaccess memory, such as DRAM, SRAM, DDR RAM or other random access solidstate memory devices; and may include non-volatile memory, such as oneor more magnetic disk storage devices, optical disk storage devices,flash memory devices, or other non-volatile solid state storage devices.Memory 228, or alternately the non-volatile memory device(s) withinmemory 228, includes a non-transitory computer readable storage medium.In some embodiments, memory 228 or the computer readable storage mediumof memory 228 stores programs, modules and data structures, and/orinstructions for displaying one or more images on electronic display215.

Electronic display 215 displays images to the user in accordance withdata received from console 210 and/or processor(s) 216. In variousembodiments, electronic display 215 may comprise a single adjustabledisplay element or multiple adjustable display elements (e.g., a displayfor each eye of a user). In some embodiments, electronic display 215 isconfigured to display images to the user by projecting the images ontoone or more reflective elements 260.

In some embodiments, the display element includes one or more lightemission devices and a corresponding array of spatial light modulators.A spatial light modulator is an array of electro-optic pixels,opto-electronic pixels, some other array of devices that dynamicallyadjust the amount of light transmitted by each device, or somecombination thereof. These pixels are placed behind one or more lenses.In some embodiments, the spatial light modulator is an array of liquidcrystal based pixels in an LCD (a Liquid Crystal Display). Examples ofthe light emission devices include: an organic light emitting diode, anactive-matrix organic light-emitting diode, a light emitting diode, sometype of device capable of being placed in a flexible display, or somecombination thereof. The light emission devices include devices that arecapable of generating visible light (e.g., red, green, blue, etc.) usedfor image generation. The spatial light modulator is configured toselectively attenuate individual light emission devices, groups of lightemission devices, or some combination thereof. Alternatively, when thelight emission devices are configured to selectively attenuateindividual emission devices and/or groups of light emission devices, thedisplay element includes an array of such light emission devices withouta separate emission intensity array. In some embodiments, electronicdisplay 215 projects images to one or more reflective elements 260,which reflect at least a portion of the light toward an eye of a user.

One or more lenses direct light from the arrays of light emissiondevices (optionally through the emission intensity arrays) to locationswithin each eyebox and ultimately to the back of the user's retina(s).An eyebox is a region that is occupied by an eye of a user locatedproximity to display device 205 (e.g., a user wearing display device205) for viewing images from display device 205. In some cases, theeyebox is represented as a 10 mm×10 mm square. In some embodiments, theone or more lenses include one or more coatings, such as anti-reflectivecoatings.

In some embodiments, the display element includes an infrared (IR)detector array that detects IR light that is retro-reflected from theretinas of a viewing user, from the surface of the corneas, lenses ofthe eyes, or some combination thereof. The IR detector array includes anIR sensor or a plurality of IR sensors that each correspond to adifferent position of a pupil of the viewing user's eye. In alternateembodiments, other eye tracking systems may also be employed. As usedherein, IR refers to light with wavelengths ranging from 700 nm to 1 mmincluding near infrared (NIR) ranging from 750 nm to 1500 nm.

Eye tracking module 217 determines locations of each pupil of a user'seyes. In some embodiments, eye tracking module 217 instructs electronicdisplay 215 to illuminate the eyebox with IR light (e.g., via IRemission devices in the display element).

A portion of the emitted IR light will pass through the viewing user'spupil and be retro-reflected from the retina toward the IR detectorarray, which is used for determining the location of the pupil.Alternatively, the reflection off of the surfaces of the eye is used toalso determine location of the pupil. The IR detector array scans forretro-reflection and identifies which IR emission devices are activewhen retro-reflection is detected. Eye tracking module 217 may use atracking lookup table and the identified IR emission devices todetermine the pupil locations for each eye. The tracking lookup tablemaps received signals on the IR detector array to locations(corresponding to pupil locations) in each eyebox. In some embodiments,the tracking lookup table is generated via a calibration procedure(e.g., user looks at various known reference points in an image and eyetracking module 217 maps the locations of the user's pupil while lookingat the reference points to corresponding signals received on the IRtracking array). As mentioned above, in some embodiments, system 200 mayuse other eye tracking systems than the embedded IR one describedherein.

Adjustment module 218 generates an image frame based on the determinedlocations of the pupils. In some embodiments, this sends a discreteimage to the display that will tile subimages together thus a coherentstitched image will appear on the back of the retina. Adjustment module218 adjusts an output (i.e. the generated image frame) of electronicdisplay 215 based on the detected locations of the pupils. Adjustmentmodule 218 instructs portions of electronic display 215 to pass imagelight to the determined locations of the pupils. In some embodiments,adjustment module 218 also instructs the electronic display to not passimage light to positions other than the determined locations of thepupils. Adjustment module 218 may, for example, block and/or stop lightemission devices whose image light falls outside of the determined pupillocations, allow other light emission devices to emit image light thatfalls within the determined pupil locations, translate and/or rotate oneor more display elements, dynamically adjust curvature and/or refractivepower of one or more active lenses in the lens (e.g., microlens) arrays,or some combination thereof.

Optional locators 220 are objects located in specific positions ondisplay device 205 relative to one another and relative to a specificreference point on display device 205. A locator 220 may be a lightemitting diode (LED), a corner cube reflector, a reflective marker, atype of light source that contrasts with an environment in which displaydevice 205 operates, or some combination thereof. In embodiments wherelocators 220 are active (i.e., an LED or other type of light emittingdevice), locators 220 may emit light in the visible band (e.g., about500 nm to 750 nm), in the infrared band (e.g., about 750 nm to 1 mm), inthe ultraviolet band (about 100 nm to 500 nm), some other portion of theelectromagnetic spectrum, or some combination thereof.

In some embodiments, locators 220 are located beneath an outer surfaceof display device 205, which is transparent to the wavelengths of lightemitted or reflected by locators 220 or is thin enough to notsubstantially attenuate the wavelengths of light emitted or reflected bylocators 220. Additionally, in some embodiments, the outer surface orother portions of display device 205 are opaque in the visible band ofwavelengths of light. Thus, locators 220 may emit light in the IR bandunder an outer surface that is transparent in the IR band but opaque inthe visible band.

IMU 230 is an electronic device that generates calibration data based onmeasurement signals received from one or more position sensors 225.Position sensor 225 generates one or more measurement signals inresponse to motion of display device 205. Examples of position sensors225 include: one or more accelerometers, one or more gyroscopes, one ormore magnetometers, another suitable type of sensor that detects motion,a type of sensor used for error correction of IMU 230, or somecombination thereof. Position sensors 225 may be located external to IMU230, internal to IMU 230, or some combination thereof.

Based on the one or more measurement signals from one or more positionsensors 225, IMU 230 generates first calibration data indicating anestimated position of display device 205 relative to an initial positionof display device 205. For example, position sensors 225 includemultiple accelerometers to measure translational motion (forward/back,up/down, left/right) and multiple gyroscopes to measure rotationalmotion (e.g., pitch, yaw, roll). In some embodiments, IMU 230 rapidlysamples the measurement signals and calculates the estimated position ofdisplay device 205 from the sampled data. For example, IMU 230integrates the measurement signals received from the accelerometers overtime to estimate a velocity vector and integrates the velocity vectorover time to determine an estimated position of a reference point ondisplay device 205. Alternatively, IMU 230 provides the sampledmeasurement signals to console 210, which determines the firstcalibration data. The reference point is a point that may be used todescribe the position of display device 205. While the reference pointmay generally be defined as a point in space; however, in practice thereference point is defined as a point within display device 205 (e.g., acenter of IMU 230).

In some embodiments, IMU 230 receives one or more calibration parametersfrom console 210. As further discussed below, the one or morecalibration parameters are used to maintain tracking of display device205. Based on a received calibration parameter, IMU 230 may adjust oneor more IMU parameters (e.g., sample rate). In some embodiments, certaincalibration parameters cause IMU 230 to update an initial position ofthe reference point so it corresponds to a next calibrated position ofthe reference point. Updating the initial position of the referencepoint as the next calibrated position of the reference point helpsreduce accumulated error associated with the determined estimatedposition. The accumulated error, also referred to as drift error, causesthe estimated position of the reference point to “drift” away from theactual position of the reference point over time.

Imaging device 235 generates calibration data in accordance withcalibration parameters received from console 210. Calibration dataincludes one or more images showing observed positions of locators 220that are detectable by imaging device 235. In some embodiments, imagingdevice 235 includes one or more still cameras, one or more videocameras, any other device capable of capturing images including one ormore locators 220, or some combination thereof. Additionally, imagingdevice 235 may include one or more filters (e.g., used to increasesignal to noise ratio). Imaging device 235 is configured to optionallydetect light emitted or reflected from locators 220 in a field of viewof imaging device 235. In embodiments where locators 220 include passiveelements (e.g., a retroreflector), imaging device 235 may include alight source that illuminates some or all of locators 220, whichretro-reflect the light towards the light source in imaging device 235.Second calibration data is communicated from imaging device 235 toconsole 210, and imaging device 235 receives one or more calibrationparameters from console 210 to adjust one or more imaging parameters(e.g., focal length, focus, frame rate, ISO, sensor temperature, shutterspeed, aperture, etc.).

In some embodiments, display device 205 optionally includes one or morereflective elements 260. In some embodiments, electronic display device205 optionally includes a single reflective element 260 or multiplereflective elements 260 (e.g., a reflective element 260 for each eye ofa user). In some embodiments, electronic display device 215 projectscomputer-generated images on one or more reflective elements 260, which,in turn, reflect the images toward an eye or eyes of a user. Thecomputer-generated images include still images, animated images, and/ora combination thereof. The computer-generated images include objectsthat appear to be two-dimensional and/or three-dimensional objects. Insome embodiments, one or more reflective elements 260 are partiallytransparent (e.g., the one or more reflective elements 260 have atransmittance of at least 15%, 20%, 25%, 30%, 35%, 50%, 55%, or 50%),which allows transmission of ambient light. In such embodiments,computer-generated images projected by electronic display 215 aresuperimposed with the transmitted ambient light (e.g., transmittedambient image) to provide augmented reality images.

Input interface 250 is a device that allows a user to send actionrequests to console 210. An action request is a request to perform aparticular action. For example, an action request may be to start or endan application or to perform a particular action within the application.Input interface 250 may include one or more input devices. Example inputdevices include: a keyboard, a mouse, a game controller, data from brainsignals, data from other parts of the human body, or any other suitabledevice for receiving action requests and communicating the receivedaction requests to console 210. An action request received by inputinterface 250 is communicated to console 210, which performs an actioncorresponding to the action request. In some embodiments, inputinterface 250 may provide haptic feedback to the user in accordance withinstructions received from console 210. For example, haptic feedback isprovided when an action request is received, or console 210 communicatesinstructions to input interface 250 causing input interface 250 togenerate haptic feedback when console 210 performs an action.

Console 210 provides media to display device 205 for presentation to theuser in accordance with information received from one or more of:imaging device 235, display device 205, and input interface 250. In theexample shown in FIG. 2, console 210 includes application store 255,tracking module 250, and application engine 255. Some embodiments ofconsole 210 have different modules than those described in conjunctionwith FIG. 2. Similarly, the functions further described herein may bedistributed among components of console 210 in a different manner thanis described here.

When application store 255 is included in console 210, application store255 stores one or more applications for execution by console 210. Anapplication is a group of instructions, that when executed by aprocessor, is used for generating content for presentation to the user.Content generated by the processor based on an application may be inresponse to inputs received from the user via movement of display device205 or input interface 250. Examples of applications include: gamingapplications, conferencing applications, video playback application, orother suitable applications.

When tracking module 250 is included in console 210, tracking module 250calibrates system 200 using one or more calibration parameters and mayadjust one or more calibration parameters to reduce error indetermination of the position of display device 205. For example,tracking module 250 adjusts the focus of imaging device 235 to obtain amore accurate position for observed locators on display device 205.Moreover, calibration performed by tracking module 250 also accounts forinformation received from IMU 230. Additionally, if tracking of displaydevice 205 is lost (e.g., imaging device 235 loses line of sight of atleast a threshold number of locators 220), tracking module 250re-calibrates some or all of system 200.

In some embodiments, tracking module 250 tracks movements of displaydevice 205 using second calibration data from imaging device 235. Forexample, tracking module 250 determines positions of a reference pointof display device 205 using observed locators from the secondcalibration data and a model of display device 205. In some embodiments,tracking module 250 also determines positions of a reference point ofdisplay device 205 using position information from the first calibrationdata. Additionally, in some embodiments, tracking module 250 may useportions of the first calibration data, the second calibration data, orsome combination thereof, to predict a future location of display device205. Tracking module 250 provides the estimated or predicted futureposition of display device 205 to application engine 255.

Application engine 255 executes applications within system 200 andreceives position information, acceleration information, velocityinformation, predicted future positions, or some combination thereof ofdisplay device 205 from tracking module 250. Based on the receivedinformation, application engine 255 determines content to provide todisplay device 205 for presentation to the user. For example, if thereceived information indicates that the user has looked to the left,application engine 255 generates content for display device 205 thatmirrors the user's movement in an augmented environment. Additionally,application engine 255 performs an action within an applicationexecuting on console 210 in response to an action request received frominput interface 250 and provides feedback to the user that the actionwas performed. The provided feedback may be visual or audible feedbackvia display device 205 or haptic feedback via input interface 250.

FIG. 3 is an isometric view of display device 300 in accordance withsome embodiments. In some other embodiments, display device 300 is partof some other electronic display (e.g., a digital microscope, ahead-mounted display device, etc.). In some embodiments, display device300 includes light emission device array 310 and one or more lenses 330.In some embodiments, display device 300 also includes an IR detectorarray.

Light emission device array 310 emits image light and optional IR lighttoward the viewing user. Light emission device array 310 may be, e.g.,an array of LEDs, an array of microLEDs, an array of OLEDs, or somecombination thereof. Light emission device array 310 includes lightemission devices 320 that emit light in the visible light (andoptionally includes devices that emit light in the IR).

In some embodiments, display device 300 includes an emission intensityarray configured to selectively attenuate light emitted from lightemission array 310. In some embodiments, the emission intensity array iscomposed of a plurality of liquid crystal cells or pixels, groups oflight emission devices, or some combination thereof. Each of the liquidcrystal cells is, or in some embodiments, groups of liquid crystal cellsare, addressable to have specific levels of attenuation. For example, ata given time, some of the liquid crystal cells may be set to noattenuation, while other liquid crystal cells may be set to maximumattenuation. In this manner, the emission intensity array is able tocontrol what portion of the image light emitted from light emissiondevice array 310 is passed to the one or more lenses 330. In someembodiments, display device 300 uses an emission intensity array tofacilitate providing image light to a location of pupil 350 of eye 350of a user, and minimize the amount of image light provided to otherareas in the eyebox.

One or more lenses 330 receive the modified image light (e.g.,attenuated light) from emission intensity array (or directly fromemission device array 310), and direct the modified image light to alocation of pupil 350.

An optional IR detector array detects IR light that has beenretro-reflected from the retina of eye 350, a cornea of eye 350, acrystalline lens of eye 350, or some combination thereof. The IRdetector array includes either a single IR sensor or a plurality of IRsensitive detectors (e.g., photodiodes). In some embodiments, the IRdetector array is separate from light emission device array 310. In someembodiments, the IR detector array is integrated into light emissiondevice array 310.

In some embodiments, light emission device array 310 and an emissionintensity array make up a display element. Alternatively, the displayelement includes light emission device array 310 (e.g., when lightemission device array 310 includes individually adjustable pixels)without the emission intensity array. In some embodiments, the displayelement additionally includes the IR array. In some embodiments, inresponse to a determined location of pupil 350, the display elementadjusts the emitted image light such that the light output by thedisplay element is refracted by one or more lenses 330 toward thedetermined location of pupil 350, and not toward other locations in theeyebox.

In some embodiments, display device 300 includes one or more broadbandsources (e.g., one or more white LEDs) coupled with a plurality of colorfilters, in addition to, or instead of, light emission device array 310.

Display device 300 also includes holographic medium 335, which isincluded in a holographic illuminator.

FIG. 4A is a schematic diagram illustrating holographic illuminator 400in accordance with some embodiments. Holographic illuminator 400includes light source 402 and holographic medium 404. Holographic medium404 is a wide-field holographic medium for projecting a plurality oflight patterns onto a surface of an eye of a user of a head-mounteddisplay device for eye-tracking purposes. In some cases, a wide-fieldholographic medium refers to a holographic medium configured toilluminate an area with a characteristic dimension of at least 10 mm(e.g., illuminating an area of at least 10 mm in diameter or length witha plurality of light patterns). In some embodiments, light source 402 isa single-point light source (e.g., a laser or an LED). In someembodiments, light source 402 is a wide-field light source. In someembodiments, light 402-1 provided by light source 402 is collimatedlight.

In FIG. 4A, light source 402 is located away from an optical axis ofholographic medium 404. In some embodiments, light source 402 is locatedaway from an optical axis of a lens (e.g., lens 330 in FIG. 3) of ahead-mounted display device. In some embodiments, light source 402 islocated away from a field of view of eye 408 (e.g., eye 408 correspondsto an eye of a user of a head-mounted display device). By providing anoff-axis illumination, light source 402 does not occlude the field ofview of eye 408. In some embodiments, light source 402 is positioned onthe optical axis of holographic medium 404.

In FIG. 4A, light 402-1 provided by light source 402 is projected towardholographic medium 404. Holographic medium 404 is a reflectionholographic medium having surface 404-1 and surface 404-2 with one ormore recorded interference patterns. The one or more recordedinterference patterns modify light impinging on recorded interferencepatterns and project one or more holographic patterns. In FIG. 4A, light402-1 is received by surface 404-2 of holographic medium 404.Holographic medium 404 includes areas 412-1, 412-2, and 412-3 that areconfigured to interact with light 402-1 and concurrently direct (e.g.,reflect, diffract, etc.) separate light patterns 406-1, 406-2, and 406-3toward eye 408. In some embodiments, light patterns 406-1, 406-2, and406-3 convergence on reference plane 410-1 adjacent to eye 408, as shownin FIG. 4A, creating three virtual single-point light sources near eye408. In FIG. 4A, light patterns 406-1, 406-2, and 406-3 are eachprojected toward eye 408 at different angles. For example, light pattern406-1 is directed toward eye 408 at a first angle, light pattern 406-2is directed toward eye 408 at a second angle, and light pattern 406-3 isdirected toward eye 408 at a third angle.

In some embodiments, holographic medium 404 has a limited angular and/orspectral selectivity. For example, holographic medium 404 reflects light402-1 with a specific wavelength range and/or with a specificdistribution of incident angles while transmitting light withwavelengths outside the specific wavelength range and/or with incidentangles outside the specific distribution of incident angles. In someembodiments, holographic medium 404 reflects light in the IR (e.g., NIR)wavelength range.

In some embodiments, holographic medium 404 is a volume hologram (alsocalled a Bragg hologram). A volume hologram refers to a hologram withthickness sufficiently large for inducing Bragg diffraction, i.e., thethickness of the recording material used for recording a volume hologramis significantly larger than the wavelength of light used for recordingthe hologram. Such holograms have spectral selectivity, angularselectivity of an incident light and/or selectivity with respect towavefront profile of an incident light.

FIG. 4B is a schematic diagram illustrating holographic illuminator 420in accordance with some embodiments. Holographic illuminator 420 issimilar to holographic illuminator 400 described above with respect toFIG. 4A, except that holographic illuminator 420 includes holographicmedium 424 instead of holographic medium 420. Holographic medium 424includes areas 422-1, 422-2, and 422-3 that are configured to interactwith light 402-1 and concurrently direct (e.g., reflect, diffract, etc.)separate light patterns 426-1, 426-2, and 426-3 toward eye 408. Lightpatterns 426-1, 426-2, and 426-3 are distinct from the correspondinglight patterns of FIG. 4A such that light patterns 426-1, 426-3, and426-3 do not converge on a plane adjacent to eye 408. Instead, lightpatterns 426-1, 426-3, and 426-3 in FIG. 4B have projected convergencepoints on reference plane 410-2 positioned on an opposite side ofholographic medium 424 from eye 408 (e.g., facing surface 424-1 ofholographic medium 424 so that reference plane 410-2 is closer tosurface 424-1 of holographic medium 424 than surface 424-2 ofholographic medium 424).

FIG. 4C is a schematic diagram illustrating holographic illuminator 430in accordance with some embodiments. Holographic illuminator 430 issimilar to holographic illuminator 400 described above with respect toFIG. 4A, except that holographic illuminator 430 includes holographicmedium 434, which is a transmission holographic medium having surfaces434-1 and 434-2. Light source 402 is positioned away from an opticalaxis of holographic medium 434 and away from a field of view of eye 408.In holographic illuminator 430, light source 402 is positioned onopposite side of holographic medium 434 from eye 408, facing surface434-1 of holographic medium 434 (e.g., light source 402 is positionedcloser to surface 434-1 of holographic medium 434 than surface 434-2 ofholographic medium 434). Holographic medium 434 includes areas 432-1,432-2, and 432-3 that are configured to interact with light 402-1 andconcurrently direct separate light patterns 436-1, 436-2, and 436-3toward eye 408. Similar to the corresponding light patterns 406-1,406-2, and 406-3 in FIG. 4A, light patterns 436-1, 436-2, and 436-3, insome embodiments, converge on reference plane 410-1 in proximity to eye408 as shown in FIG. 4C, creating three virtual single-point lightsources near eye 408. In some embodiments, light patterns 436-1, 436-2,and 436-3 have projected convergence points on a reference plane (e.g.,reference plane 410-2 in FIG. 4B) positioned on opposite side ofholographic medium 434 (e.g., facing surface 4341 of holographic medium434).

FIG. 4D is a schematic diagram illustrating holographic illuminator 400shown in FIG. 4A. As explained above with respect to FIG. 4A, lightpatterns projected by holographic medium 404 (e.g., light patterns 406-1and 406-2) are projected toward eye 408 at respective angles. FIG. 4Aillustrates holographic illuminator 400 with reference line 442representing the direction of light pattern 406-1 projected toward eye408 and reference line 444 representing the direction of light pattern406-2 projected toward eye 408. In FIG. 4D, reference line 440corresponds to an optical axis of eye 408. As illustrated withrespective reference lines 442 and 444, the direction of light pattern406-1 is distinct from the direction of light pattern 406-2. In FIG. 4D,light pattern 406-1, which is the outermost light pattern projected byholographic medium 404, is projected toward eye 408 at a 53-degree anglewith respect to reference line 440 and light pattern 406-2 is projectedtoward eye 408 at a 20-degree angle with respect to reference line 440.In some embodiments, light pattern 406-1 is projected toward eye 408 atan angle ranging from 30 to 40 degrees. In some embodiments, lightpattern 406-1 is projected toward eye 408 in an angle ranging from 40 to50 degrees. In some embodiments, light pattern 406-1 is projected towardeye 408 in an angle ranging from 50 to 55 degrees. In some embodiments,light pattern 406-1 is projected toward eye 408 in an angle of 45degrees or more.

FIG. 4E is a schematic diagram illustrating holographic illuminator 450in accordance with some embodiments. Holographic illuminator 450includes holographic medium 454 coupled with waveguide 456. In someembodiments, holographic medium 454 corresponds to holographic medium404 described above with respect to FIG. 4A. Waveguide 456 is opticallycoupled with light source 402 and configured to receive light 402-1projected by light source 402. In some embodiments, waveguide includes,or is coupled with, in-coupling element 452. In some embodiments,in-coupling element 452 is a prism or a diffractive or holographicstructure (e.g., a surface relief grating or a volume hologram).In-coupling element 452 is configured to receive light 402-1 andtransmit light 402-1 to waveguide 456 in such an angle that light 402-1propagates through waveguide 456 by internal reflection, as illustratedwith light 402-2. Holographic medium 454 acts as an out-coupling elementsuch that when light 402-2 propagating through waveguide 456 interactswith holographic medium, the light is emitted as a plurality of lightpatterns (e.g., light patterns 454-1 and 454-2). In some embodiments,light patterns 454-1 and 454-2 correspond to light patterns 406-1,406-2, and 406-3 reflected toward eye 408 described above with respectto FIG. 4A. In some embodiments, holographic illuminator 450 withwaveguide 456 is configured to reduce the distance between light source402 and holographic medium 454 in a direction parallel to an opticalaxis of holographic medium 454, thereby making holographic illuminator450 more compact.

FIGS. 5A-5F are schematic diagrams illustrating configurations of lightpatterns used for eye tracking in accordance with some embodiments. Theexample light patterns illustrated in FIGS. 5A-5F are used for in-fieldillumination of an eye. In some embodiments, the eye is illuminated withan IR or NIR light for eye-tracking purposes (e.g., the light patternsillustrated in FIG. 5A-5F are illuminated with an IR or NIR light). Insome embodiments, the light patterns shown in FIG. 5A-5F are configuredto illuminate an area with a characteristic dimension (e.g., a diameteror width) of at least 10 mm on a surface of the eye. The configurationsshown in FIGS. 5A-5F include a plurality of distinct and separate lightpatterns (e.g., image objects or image structures, such as lightpatterns 502-1, 502-2, and 502-3 in FIG. 5A), arranged in a uniform or anon-uniform configuration. In some embodiments, a number of patterns inthe plurality of separate light patterns is between 5 and 2000. In someembodiments, the number of light patterns in a particular configurationis between seven and twenty. In some embodiments, the number of lightpatterns is between 20 and 1000. In some embodiments, the number oflight patterns is between 1000 and 2000. In some embodiments, the lightpatterns have one or more predefined shapes, such as circles (e.g.,spots), stripes, triangles, squares, polygons, crosses, sinusoidalobjects and/or any other uniform or non-uniform shapes.

FIG. 5A illustrates configuration 502 including seven separate lightpatterns (e.g., light patterns 502-1, 502-2, and 502-3). In FIG. 5A,each light pattern has a shape of a circle (e.g., a solid circle or ahollow circle). Multiple light patterns (e.g., light patterns 502-1 and502-2 among others) are arranged in a circular configuration with lightpattern 502-3 positioned at the center of the circular configuration. Insome embodiments, configuration 502 includes light patterns arranged ina plurality of concentric circles (e.g., 2, 3, 4, 5 circles or more). Insome embodiments, configuration 502 does not include a central lightpattern (e.g., light pattern 502-3).

FIG. 5B illustrates rectangular configuration 504 including a plurality(e.g., eight) of separate stripe-shaped light patterns (e.g., lightpatterns 504-1 and 504-2).

FIG. 5C illustrates configuration 506 including a plurality of lightpatterns arranged in a two-dimensional configuration (e.g., arectangular configuration). In FIG. 5C, the plurality of light patternsis arranged in multiple rows and multiple columns (e.g., 144 lightpatterns arranged in twelve rows and twelve columns). In someembodiments, the plurality of light patterns is arranged to have auniform spacing in a first direction and a uniform spacing in a seconddirection that is distinct from the first direction (e.g., the seconddirection is orthogonal to the first direction). In some embodiments,the plurality of light patterns is arranged to have a first spacing inthe first direction and a second spacing in the second direction that isdistinct from the first spacing. In some embodiments, the plurality oflight patterns is arranged to have a uniform spacing in the firstdirection and a non-uniform spacing in the second direction. In someembodiments, the plurality of light patterns is arranged to have auniform center-to-center distance in the first direction and a uniformcenter-to-center distance in the second direction. In some embodiments,the plurality of light patterns is arranged to have a firstcenter-to-center distance in the first direction and a secondcenter-to-center distance in the second direction that is distinct fromthe first center-to-center distance. In some embodiments, the pluralityof light patterns is arranged to have a uniform center-to-centerdistance in the first direction and a non-uniform center-to-centerdistance in the second direction.

In FIG. 5C, each light pattern has a same shape (e.g., a square,rectangle, triangle, circle, ellipse, oval, star, polygon, etc.).

FIG. 5D is similar to FIG. 5C, except that, in FIG. 5D, configuration507 of the plurality of light patterns includes a first set of lightpatterns 506-1 each having a first shape (e.g., a square or a rectangle)and a second set of light patterns 506-2 each having a second shape(e.g., a circle) that is distinct from the first shape.

FIG. 5E illustrates configuration 508 (e.g., a pincushion shape as shownin FIG. 5E, a barrel shape, etc.) including distorted square-shapedlight patterns (e.g., light patterns 508-1 and 508-2, among others).Configuration 508 shown in FIG. 5E is configured to account for thecontoured surface profile of an eye so that when configuration 508 oflight patterns, or at least a portion of configuration 508 of lightpatterns, is reflected off from the surface of the eye, the capturedreflections (e.g., reflected glints) are arranged in a non-distortedconfiguration (e.g., in a rectangular arrangement). For example,configuration 508 of light patterns arranged in the pincushion shapeshown in FIG. 5E is configured so that the reflection of configuration508 of light patterns projects at least a subset of the light patternsarranged in a rectangular configuration (e.g., an image of the lightpatterns reflected by the surface of the eye shows the light patternsarranged in a rectangular arrangement as shown in FIG. 5C).

FIG. 5F illustrates an image of light patterns arranged in pincushionconfiguration 510. The light patterns shown in FIG. 5F (e.g., lightpatterns 510-1, 510-2, and 510-3) have a shape of a circle.

In some embodiments, light patterns of a respective configuration havesame characteristics, such as shape, size, intensity, and/or wavelength.In some embodiments, light patterns of a respective configuration havedifferent characteristics. For example, in FIG. 5F, light pattern 510-1has a smaller size than light pattern 510-2. In some embodiments, lightpattern 510-1 is illuminated with lower intensity that light pattern510-2. In some embodiments, light pattern 510-1 is illuminated withdifferent wavelength than light pattern 510-2.

FIG. 6A is a schematic diagram illustrating display device 600 inaccordance with some embodiments. In some embodiments, display device600 is configured to provide virtual reality content to a user. In someembodiments, display device 600 corresponds to display device 100described above with respect to FIG. 1. In FIG. 6A, display device 600includes light source 402, holographic medium 404, detector 602, display610 and one or more lenses 608. Holographic medium 404 optically coupledwith light source 402 operates as a holographic illuminator describedabove with respect to FIG. 4A. Light source 402 provides light 402-1received by holographic medium 404, which then projects the light aslight patterns 406-1, 406-2, and 406-3 toward eye 408. Detector 602captures an image (e.g., an image of an area defined by rays 608-1) ofat least a portion of light patterns 406-1, 406-2, and 406-3 reflectedoff a surface (e.g., a sclera) of eye 408 directed by holographic medium404 toward detector 602 for determining a position of a pupil of eye408.

Holographic medium 404, light source 402 and detector 602 of aneye-tracking system are configured to determine a position of the pupilof eye 408 and/or track its movement as eye 408 rotates toward differentgaze directions. In some embodiments, the eye tracking systemcorresponds to, is coupled with, or is included in eye tracking module217 described herein with respect to FIG. 2. In some embodiments,detector 602 is an IR and/or NIR camera (e.g., a still camera or a videocamera) or other IR and/or NIR sensitive photodetector (e.g., an arrayof photodiodes). In some embodiments, determining a position of thepupil includes determining the position of the pupil on an x-y plane ofthe pupil (e.g., reference plane 408-1). In some embodiments, the x-yplane is a curvilinear plane. In some embodiments, detector 602 isintegrated with light source 402. In some embodiments, light projectedby light source 402 (e.g., light 402-1) and an image captured bydetector 602 (e.g., an image of an area defined by rays 608-1) have thesame optical path (or parallel optical paths) and are transmitted orguided by the same optical elements (e.g., holographic medium 404).

In some embodiments, the position of the pupil of eye 408 is determinedbased on a representative intensity or intensities of detected glints.In some embodiments, the position of the pupil is determined based on anincident angle of detected glints (e.g., display device 600 includes oneor more optical elements to determine the incident angle of the detectedglint). For example, the position of the pupil is determined bycomparing an incident angle of reflected light patterns 406-1, 406-2,and 406-3 to an estimated surface profile of the surface of eye 408. Thesurface profile of an eye does not correspond to a perfect sphere butinstead has a distinct curvature in the area that includes the corneaand the pupil. Therefore, a position of the pupil can be determined bydetermining the surface profile of the eye.

In some embodiments, at least a portion of light patterns 406-1, 406-2,and 406-3 impinges on other surfaces of eye 408 than sclera (e.g., thepupil). In some embodiments, the position of the pupil is determinedbased on a portion of light patterns 406-1, 406-2, and 406-3 impingingon the sclera and impinging on the other surfaces of eye 408. In someembodiments, the position of the pupil of eye 408 is determined based ona difference (and/or a ratio) between an intensity of a portion of lightpatterns 406-1, 406-2, and 406-3 impinging on the sclera and on thepupil. For example, the intensity of the portion of light patternsreflected on the sclera of eye is higher than the intensity the portionof light patterns reflected on the pupil and therefore the location ofthe pupil can be determined based on the intensity difference.

In some embodiments, the position of the pupil of eye 408 is determinedbased on a difference in a configuration (e.g., configurations describedabove with respect to FIG. 5A-5F) projected by the holographicilluminator and a configuration captured by detector 602. For example,as a light with a specific configuration is reflected off the non-flatsurface of eye 408, the structured pattern is modified (e.g.,distorted). The non-flat surface profile of eye 408 is then determinedbased on the distorted structured pattern and the position of the pupilis determined based on the surface profile.

In FIG. 6A, light source 402 and detector 602 are located away from anoptical axis of holographic medium 404, as well as away from opticalaxes of one or more lenses 608 and display 610. For example, lightsource 402 and detector 602 are position on a temple and/or a frame of ahead-mounted display device. Furthermore, light source 402 and detector602 are positioned away from a field-of-view of eye 408 so that they donot occlude display 610. In FIG. 6A, holographic medium 404 ispositioned adjacent to one or more lenses 608. Holographic medium 404 isconfigured to provide light patterns 406-1, 406-2, and 406-3 in thefield-of-view of eye 408. In FIG. 6A, holographic medium 404 is areflection holographic medium, and light source 402 is located toilluminate a surface of holographic medium 404 that is configured toface eye 408.

In some embodiments, holographic medium 404 is wavelength selective,thereby reflecting light 402-1 with specific wavelength range whiletransmitting light with other wavelengths, such as light from display610. In some embodiments, light 402-1 used for eye-tracking is IR or NIRlight, and therefore does not interfere with visible light projectedfrom display 610.

FIG. 6B is a schematic diagram illustrating display device 620 inaccordance with some embodiments. Display device 620 is similar todisplay device 600 described above with respect to FIG. 6A, except thatholographic medium 404 is a transmission holographic medium and lightsource 402 is located to illuminate a surface of holographic medium 404that is configured to face away from eye 408 (e.g., configured to facedisplay 610).

FIG. 6C is a schematic diagram illustrating display device 630 inaccordance with some embodiments. Display device 630 includes displaydevice 600-A for eye 408-A (e.g., the left eye of a user of ahead-mounted display device 630) and display device 600-B for eye 408-B(e.g., the right eye of a user of a head-mounted display device 630). Insome embodiments, each of display devices 600-A and 600-B corresponds todisplay device 600 described above with respect to FIG. 6A. In someembodiments, a head-mounted display includes two display devices, eachcorresponding to display device 620 described above with respect to FIG.6B. In some embodiments, display device 630 corresponds to displaydevice 100 described above with respect to FIG. 1.

FIG. 6D is a schematic diagram illustrating display device 640 inaccordance with some embodiments. Display device 640 is similar todisplay device 600 described above with respect to FIG. 6A, except thatdisplay device 640 is configured for providing augmented reality contentto a user. Display device 640 includes display 642 (or a lightprojector) positioned in adjacent to light source 402 (e.g., positionedon a temple of a head-mounted display device). Display 642 projectslight 642-1 toward beam combiner 644. Beam combiner 644 reflects and/orguides at least a portion of light 642-1 toward eye 408. Beam combiner644 combines light 642-1 with light (e.g., light 650) coming from theoutside of display device 640 (e.g., ambient light) so that an imagerepresented by light 642-1 is overlapped with, or superimposed on, areal-world image provided by light 650. In some embodiments, beamcombiner 644 is a polarization-dependent reflector that is configured toreflect light having a first polarization and transmits light having asecond polarization that is distinct from the first polarization. Insome embodiments, beam combiner 644 is an angle-dependent reflector thatis configured to reflect light having a first incident angle andtransmit light having a second incident angle that is distinct from thefirst incident angle (e.g., the second incident angle is less than thefirst incident angle).

FIG. 7A is an image illustrating a plurality of light patterns projectedon (and reflected off) one or more surfaces of an eye in accordance withsome embodiments. Sections A and B of FIG. 7A are images of a model eyecaptured by a detector of an eye-tracking system (e.g., detector 602 ofdisplay device 600 described above with respect to FIG. 6A) when areference eye is in different positions. Section A of FIG. 7Aillustrates a plurality of glints, including glint 702-A, arranged in acircle when a reference eye is at a first position and Section B of FIG.7A illustrates a plurality of glints, including glint 702-B, when thereference eye is at a second position. A position of a pupil of thereference eye can be determined based on the captured images. In someembodiments, the position of a pupil of the reference eye is determinedbased on intensities of respective glints. For example, glint 702-A inSection A has a lower intensity than the corresponding glint 702-B inSection B. This indicates that the pupil of the eye is tilted towardglint 702-B (e.g., glint 702-B is projected on the pupil so that glint702-B is not reflected or reflected at a lower intensity than glintsreflected off an iris of the eye). In some embodiments, the position ofthe pupil of the reference eye is determined based on locations ofrespective glints, such as locations of glints 702-A and 702-B.

FIG. 7B is an image illustrating a plurality of light patterns projectedby a light source (Section A of FIG. 7B) and a plurality of lightpatterns imaged from one or more surfaces of an eye (Section B of FIG.7B) in accordance with some embodiments. Section A is an example imageof a plurality of separate image patterns (e.g., plurality of lightpatterns 704) projected by a holographic illuminator. The patterns inSection A are arranged in a pincushion configuration (e.g.,corresponding to the configuration described with respect to FIG. 5E).The pincushion configuration is configured to counter for a surfaceprofile of an eye so that the light patterns reflected off the surfaceof the eye are configured in a non-distorted configuration (e.g., arectangle). Section B of FIG. 7B is an exemplary image captured by adetector of an eye-tracking system, (e.g., detector 602 of displaydevice 600 described above with respect to FIG. 6A). The image inSection B of FIG. 7B illustrates plurality of glints 706 reflected offone or more surfaces of the reference eye, arranged in a rectangularconfiguration. In some embodiments, the position of the pupil of thereference eye is determined based on the detected glints (e.g., theintensity and/or the presence-absence of respective glints). In FIG. 7B,the pincushion shape in Section A is modified by the surface profile ofthe reference eye to have the rectangular shape as shown in Section B.The position of the pupil is determined based on the surface profile ofthe reference eye (which is determined based on the arrangement ofdetected glints).

FIG. 8A is a schematic diagram illustrating system 800 for generating awide-field holographic medium in accordance with some embodiments.System 800 includes light source 802. In some embodiments, light source802 is a point-light source (e.g., a laser). In some embodiments, beam830 provided by light source 802 is coherent light. Light source 802 isoptionally coupled optically with a plurality of optical components formodifying beam 830, such as beam expander 804 that expands beam 830 andaperture 806 for adjusting the beam size of beam 830. In someembodiments, beam 830 provided by light source 802 has a beam size withdiameter less than 1 mm, which is then expanded to a beam size with adiameter greater than 10 mm, which is, in turn, clipped to a beam sizewith a diameter between 7 mm and 9 mm by aperture 806.

In some embodiments, system 800 includes polarizer 808 and apolarization of beam 830 is adjusted by polarizer 808. For example, insome implementations, polarizer 808 is a half-wave plate configured toadjust a direction of a linear polarized light.

In FIG. 8A, beam 830 is divided into two physically separated beams832-A and 834-A by beam splitter 810. In some embodiments, beam splitter810 is a 50/50 reflector (e.g., beam 832-A and beam 834-A have the sameintensity). In some embodiments, beam splitter 810 is a polarizing beamsplitter dividing beam 830 into beam 832-A with a first polarization(e.g., polarization in the vertical direction) and beam 834-A with asecond polarization (e.g., polarization in the horizontal direction). Insome embodiments, a combination of a half-wave plate (e.g., polarizer808) and a polarizing beam splitter (e.g., beam splitter 810) is usedfor adjusting intensities of beams 832-A and 834-A and/or adjusting aratio of intensities of beams 832-A and 834-A. For example, in someimplementations, the intensities are adjusted by changing theorientation of the half-wave plate. In some embodiments, thepolarization of one or more of the beams 832-A and 834-A is furtheradjusted by one or more polarizers (e.g., polarizer 812, which can be ahalf-way plate). In FIG. 8A, polarizer 812 of a second set of opticalelements 800-B adjusts the polarization of beam 834-A to correspond tothe polarization of beam 832-A. In some implementations, polarizer 812is included in a first set of optical elements 800-A for adjusting thepolarization of beam 832-A.

Beam 832-A is directed, for example by beam splitter 810, toward thefirst set of optical elements 800-A. The first set of optical elements800-A includes optical elements for providing a wide-field illuminationserving as a reference light in a formation of a holographic medium. Insome embodiments, the first set of optical elements 800-A includesreflector 822-1, which directs beam 832-A toward lens 824-1. In someembodiments, the first set of optical elements 800-A includes lens 824-1for expanding beam 834-A and transmitting wide-field beam 832-B towardoptically recordable medium 826. In some embodiments, the first set ofoptical elements 800-A includes a subset, or a superset of opticalcomponents illustrated in FIG. 8A. For example, the first set of opticalelements 800-A may include other optical elements, that are notillustrated in FIG. 8A, for providing a wide-field illumination ontooptically recordable medium 826. In some implementations, the first setof optical elements 800-A may not include one or more optical elementsillustrated as components of the first set of optical elements 800-A inFIG. 8A. A wide-field beam has a spot size applicable for illuminating,with a single exposure, an area on optically recordable medium 826 forforming any of the holographic mediums described above with respect toFIGS. 4A-4D. In some embodiments, a wide-field beam refers to a beamwith a spot size with a characteristic dimension (e.g., a diameter orwidth) of at least 10 mm. In some embodiments, a wide-field beam refersto a beam with a spot size with a characteristic dimension (e.g., adiameter or width) of at least 100 mm. In some embodiments, lens 824-1is a microscopic objective (e.g., lens 824-1 is a microscopic objectivewith 20× magnification with numerical aperture of 0.4). In someembodiments, lens 824-1 is a lens assembly including two or more lenses.Optionally, lens 824-1 is optically coupled with aperture 828-1 foradjusting a size of beam 832-B. In some embodiments, aperture 828-1 hasa diameter between 5 mm and 6 mm. In some embodiments, aperture 828-1has a diameter between 6 mm and 7 mm. In some embodiments, aperture828-1 has a diameter between 7 mm and 8 mm. In some embodiments,aperture 828-1 has a diameter between 8 mm and 9 mm. In someembodiments, aperture 828-1 has a diameter between 9 mm and 10 mm. Insome embodiments, aperture 828-1 has a diameter between 10 mm and 11 mm.In some embodiments, reflector 822-1 is an adjustable reflectorconfigured for adjusting the direction of beam 832-A, thereby adjustingthe direction of wide-field beam 832-B transmitted from lens 824-1toward optically recordable medium 826. In some implementations,wide-field beam 832-B provides a single-shot off-axis illumination witha diameter of at least 10 mm (e.g., 100 mm or more) onto surface 826-1of optically recordable medium 826.

In some embodiments, optically recordable medium 826 includesphotosensitive polymers, silver halide, dichromatic gelatin and/or otherstandard holographic materials. In some embodiments, opticallyrecordable medium 826 includes other types of wavefront shapingmaterials (e.g., metamaterials, polarization sensitive materials, etc.).In some embodiments, optically recordable medium 826 has a thickness(e.g., distance between surfaces 826-1 and 826-2) that is much greaterthan the wavelength of lights 832-B and 834-B in order to record avolume hologram.

In some embodiments, optically recordable medium 826 is coupled with awaveguide (e.g., waveguide 456 in FIG. 4E) in order to record aholographic medium (e.g., holographic medium 454) that is configured toreceive light propagating through a waveguide, as described above withrespect to holographic illuminator 450 in FIG. 4E.

Beam 834-A is directed, by beam splitter 810, toward the second set ofoptical elements 800-B. The second set of optical elements 800-Bincludes optical elements for providing a wide-field illumination to athird set of optical elements 800-C.

In some embodiments, the second set of optical elements 800-B includeslens 814-1 and parabolic reflector 816. In some embodiments, the secondset of optical elements 800-B includes a subset, or a superset ofoptical components illustrated in FIG. 8A. For example, the first set ofoptical elements 800-A may include other optical elements, that are notillustrated in FIG. 8A, for providing a wide-field illumination to thethird set of optical elements 800-C. In some implementations, the secondset of optical elements 800-B may not include one or more opticalelements illustrated as components of the second set of optical elements800-B in FIG. 8A.

In some embodiments, lens 814-1 is a microscopic objective (e.g., lens814-1 is a microscopic objective with 20× magnification and a numericalaperture of 0.4) configured to expand beam 834-A. In some embodiments,lens 814-1 is a lens assembly including two or more lenses. In FIG. 8A,lens 814-1 transmits beam 834-A toward parabolic reflector 816.Parabolic reflector 816 collimates beam 834-A and reflects collimatedwide-field beam 834-B toward the third set of optical elements 800-C. Insome embodiments, parabolic reflector 816 is positioned in 45-degreeangle with respect an optical axis of beam 834-A transmitted throughlens 814-1. In some embodiments, the combination of lens 814-1 andparabolic reflector 816 expands beam 834-A such that beam 834-B has abeam diameter of 10 mm or more. For example, the combination of lens814-1 and parabolic reflector 816 is configured to expand beam 834-Awith a beam diameter of 8 mm into a wide-field beam 834-B with a beamdiameter of 100 mm.

In FIG. 8A, parabolic reflector 816 of the second set of opticalelements 800-B is located to intersect with an optical axis of theholographic medium formed from optically recordable medium 826 (e.g., anaxis that is perpendicular to the holographic medium). In someimplementations, parabolic reflector 816 reflects beam 834-B ontooptically recordable medium 826 in a direction perpendicular tooptically recordable medium 826, thereby providing an on-axisillumination onto surface 826-2 of optically recordable medium 826 whilebeam 832-B provides an off-axis illumination onto surface 826-1 ofoptically recordable medium 826.

The third set of optical elements 800-C receives wide-field beam 834-Band project the beam as a plurality of light patterns 836 towardoptically recordable medium 826 for forming a holographic medium. System800 is configured to form holographic mediums described above withrespect to FIGS. 4A-4B. The holographic mediums formed by formed bysystem 800 are configured to project configurations such as any of thosedescribed above with respect to FIGS. 5A-5F. In some embodiments, thethird set of optical elements 800-C includes condenser lens 818 andlenses 820. Condenser lens 818 is configured to transmit wide-field beam834-B through lenses 820. In some embodiments, condenser lens 818focuses wide-field beam 834-B toward a reference pupil (e.g., theposition of the reference pupil corresponding to a position of a pupilof an eye of a user of a display device, such as eye 408 in FIG. 6A).Different embodiments of the third set of optical elements 800-C aredescribed below with respect to FIGS. 9A-9L.

FIG. 8B is a schematic diagram illustrating system 840 for generating awide-field holographic medium in accordance with some embodiments.System 840 is similar to system 800 described above with respect to FIG.8A, except that the first set of optical elements 800-A includingreflective mirror 822-2, lens 824-2 and aperture 828-2 in FIG. 840 isconfigured to provide wide-field beam 832-B onto surface 826-2 ofoptically recordable medium 826 (e.g., both the first set of opticalelements 800-A and the second set of optical elements 800-B providewide-field beams 832-B and 834-B onto a same surface of opticallyrecordable medium 826). System 840 is configured to form holographicmediums described above with respect to FIG. 4C.

FIG. 8C is a schematic diagram illustrating selection of a direction ofreference beam 832-B onto optically recordable medium 826 for generatinga wide-field holographic medium in accordance with some embodiments.Section A of FIG. 8C illustrates a portion of system 800 described abovewith respect to FIG. 8A including lens 824-1 transmitting beam 832-Bthrough aperture 828-1 onto optically recordable medium 826. Angle A′describes an angle at which beam 832-B is transmitted by lens 824-1toward optically recordable medium 826, with respect to a reference lineperpendicular to optically recordable medium 826. Section B of FIG. 8Cillustrates holographic illuminator 400 described above with respect toFIG. 4A with light source 402 and holographic medium 404 projecting aplurality of light patters toward eye 408. Angle A″ describes an angleat which light 402-1 is projected toward holographic illuminator 404 bylight source 402, with respect to a reference line perpendicular toholographic medium 404. In some embodiments, Angle A′ at which beam832-B in Section A is transmitted toward optically recordable medium 826is selected to correspond to Angle A″ at which light source 402 directslight 402-1 toward holographic medium 404. In some embodiments, Angle A′is adjusted by reflector 822-1 shown in FIG. 8A.

FIG. 9A is a schematic diagram illustrating a side view of opticalelements 900 for generating a holographic medium in accordance with someembodiments. Optical elements 900 is similar to the third set of opticalelements 800-C described above with respect to FIG. 8A. In FIG. 9A,three lenses (e.g., lenses 820-A, 820-B, and 820-C) of lenses 820-1 areillustrated. Wide-field beam 834-B, received from the second set ofoptical elements 800-B in system 800, is transmitted through condenserlens 818. Condenser lens 818 is configured to transmit wide-field beam834-B, through lenses 820-1, toward reference pupil 903 (e.g., in somecases, reference pupil 903 corresponding to a pupil of an eye of a userof a display device, such as eye 408 in FIG. 6A). In some embodiments,condenser lens 818 has a diameter ranging from 50 mm to 100 mm. In someembodiments, condenser lens 818 has a diameter of 75 mm.

Condenser lens 818 is optically coupled with lenses 820-1, includinglenses 820-A, 820-B, and 820-C. In some embodiments, lenses 820-1 areattached to or coupled with condenser lens 808. In some embodiments,lenses 820-1 are positioned adjacent to, but separated from, condenserlens 808. In some embodiments, lenses 820-1 are positioned adjacent tooptically recordable medium 826. Each lens of lenses 820-1 focuses arespective portion of wide-field beam 834-B as a respective lightpattern of light patterns 836. In FIG. 9A, lens 820-A projects a portionof beam 834-B as pattern 836-A, lens 820-B projects a portion of beam834-B as pattern 836-B, and lens 820-C projects a portion of beam 834-Bas pattern 836-C. Pattern 836-A is projected toward optically recordablemedium 826 at an angle different from an angle of projection of pattern836-B. The angles at which light patterns 836-A and 836-B are projectedtoward the reference eye correspond to the respective angles at whichlight patterns 406-1 and 406-2 are projected toward the pupil of eye 408in FIG. 4D. In some embodiments, light pattern 836-A projected by lens820-A, which is the outermost lens of lenses 820-1, is projected towardreference pupil 903 (e.g., reference pupil 903 corresponding to eye 408in FIG. 4D). In some embodiments, light pattern 836-A is projectedtoward reference pupil 903 at an angle ranging from 40 to 50 degrees. Insome embodiments, light pattern 836-A is projected toward referencepupil 903 at an angle ranging from 50 to 55 degrees. In someembodiments, light pattern 836-A is projected toward reference pupil 903at angle 45 degrees or more.

In FIG. 9A, light patterns 836 converge on reference plane 902.Reference plane 902 is positioned between optically recordable medium826 and lenses 820-1. In some embodiments, reference line 902corresponds to reference line 410-1 shown in FIG. 4A. In someembodiments, optical elements 900 are configured to form a holographicmedium corresponding to holographic medium 404 in FIG. 4A. Theholographic medium transmits light patterns 406-1, 406-2, and 402-3toward eye 408 so that the convergence points of light patterns 406-1,406-2, and 402-3 create a plurality of virtual single-point lightsources near the surface of eye 408. In some embodiments, opticalelements 900 are configured to form a holographic medium correspondingto holographic medium 424 in FIG. 4B that transmits light patterns426-1, 426-2, and 426-3 toward eye 408 so that projected convergencepoints of light patterns 426-1, 426-2, and 426-3 create a plurality ofvirtual single-point light sources on an opposite side of holographicmedium 424 (e.g., facing surface 424-1 of holographic medium 424).

In some embodiments, lenses 820-1 are coupled with a plurality ofoptical attenuators (e.g., attenuators 904-A and 904-B). Attenuator904-A is coupled with lens 820-A and configured to attenuate anintensity of light pattern 836-A. Attenuator 904-B is coupled with lens820-B and configured to attenuate an intensity of light pattern 836-B.In some embodiments, the attenuators are adjustable attenuators. In someembodiments, the attenuators are fixed intensity attenuators.

In some embodiments, lenses 820-A and 820-B are microlenses. In someembodiments, lenses 820-1 are arranged in a microlens array. Lenses820-1 include a number of lenses ranging from seven to 2000. In someembodiments, the number of lenses ranges from seven to 20 lenses. Insome embodiments, the number of lenses ranges from 20 to 1000 lenses. Insome embodiments, the number of lenses ranges from 1000 to 2000 lightlenses. In some embodiments, each lens of lenses 820-1 projects a lightpattern corresponding to an area on the holographic medium, such thateach area is configured to transmit a light pattern (e.g., areas 412-1,412-2, and 412-3 of holographic medium 404 transmitting respective lightpatterns 406-1, 406-2, and 406-3 in FIG. 4A). In some embodiments,lenses 820-1 are arranged in a circular, rectangular, square,triangular, polygonal, distorted configuration (e.g., a pincushionshaped configuration) and/or any other uniform or non-uniformconfiguration. Lenses 820-1 are arranged to form an interference patternthat creates a holographic medium that projects a plurality of separatelight patterns arranged in a particular configuration, including any ofthe configurations described above with respect to FIGS. 5A-5F.

FIG. 9B is a schematic diagram illustrating a plan view of lenses 820-2(e.g., a lens array) for generating a holographic medium in accordancewith some embodiments. In some embodiments, lenses 820-2 correspond tolenses 820-1 described with respect to FIG. 9A (e.g., lenses 820-1 arearranged in the configuration shown in FIG. 9B). FIG. 9B includes anarray of 20 by 20 lenses arranged in a rectangular configuration.

FIG. 9C is a schematic diagram illustrating a plan view of lenses 820-3for generating a holographic medium in accordance with some embodiments.In some embodiments, lenses 820-3 correspond to lenses 820-1 describedwith respect to FIG. 9A (e.g., lenses 820-1 are arranged in theconfiguration shown in FIG. 9C). FIG. 9C includes a lens array includingeight lenses in a circular configuration.

FIG. 9D is a schematic diagram illustrating a side view of opticalelements 900 for generating a holographic medium in accordance with someembodiments. In some embodiments, lenses 921 include 30 or more lenses(e.g., a microlens array of lenses). FIG. 9D also illustrates opticalpaths of a plurality of rays being transmitted through condenser lens818, and projected by lenses 820-1 toward optically recordable medium826 as a plurality of light patterns 936.

FIG. 9E is a schematic diagram illustrating a side view of opticalelements 910 for generating a holographic medium in accordance with someembodiments. Optical elements 910 are similar to the third set ofoptical elements 800-C described above with respect to FIG. 8A forproviding a plurality of light patterns (e.g., light patterns 836) ontooptically recordable medium 826 for forming a holographic medium, expectthat optical elements 910 include prisms 912 (e.g., prisms 912-A and912-B). Prisms 912 are configured to received wide-field beam 834-B andproject the beam as a plurality of beams onto optically recordablemedium 826. In some embodiments, the number of prisms 912 and/or theconfigurations of prisms 912 are selected to provide any configurationof a plurality of light patterns described herein (e.g., configurationsillustrated in FIGS. 5A-5F). In some embodiments, prisms 912 areoptically coupled with lenses 921, as shown in FIG. 9E. Lenses 921receive the plurality of beams projected by prisms 912 and project aplurality of light patterns toward optically recordable medium 826 in amanner similar to lenses 820-1 described with respect to FIG. 9A.

In FIG. 9E, lenses 921 and prisms 912 are arranged in a domeconfiguration adjacent to optically recordable medium 826, so that theperipheral prisms and lenses (e.g., prism 912-A and lens 921-A) arepositioned closer to optically recordable medium 826 than the prisms andlenses positioned in the center (e.g., prism 912-B and lens 921-B). Forexample, distance D1 between prism 912-A and optically recordable medium826 is less than distance D2 between prism 912-B and opticallyrecordable medium 826. Similarly, a distance between lens 921-A andoptically recordable medium 826 is less than a distance between lens921-B and optically recordable medium 826.

FIG. 9F is a schematic diagram illustrating optical elements 910 forgenerating a holographic medium in accordance with some embodiments.FIG. 9F illustrates a three-dimensional view of optical elements 910including prisms 912 optically coupled with lenses 921. In someembodiments, prisms 912 are arranged in multiple concentric circlesdefining a dome configuration. In FIG. 9F, prisms 912 includes twelveprisms arranged in a dome configuration (e.g., four prisms in an innercircle and eight prisms in an outer circle).

FIG. 9G is a schematic diagram illustrating a side view of opticalelements 910 for generating a holographic medium in accordance with someembodiments. FIG. 9G illustrates optical paths of a plurality of raysbeing transmitted through prisms 912 and lenses 921 toward opticallyrecordable medium 826.

FIGS. 9H-9J are schematic diagrams illustrating side views of opticalelements 920 for generating a holographic medium in accordance with someembodiments. Optical elements 920 are similar to the third set ofoptical elements 800-C described above with respect to FIG. 8A forproviding a plurality of light patterns (e.g., light patterns 836) ontooptically recordable medium 826 for forming a holographic medium, expectthat optical elements 920 include parabolic reflectors 922 (e.g.,parabolic reflectors 922-A and 922-B) instead of lenses 820. In someembodiments, parabolic reflectors 922 are replaced by ellipsoidalreflectors and/or freeform shaped reflectors. In some embodiments, thenumber of parabolic reflectors 922 and/or the configurations ofparabolic reflectors 922 are selected to provide any configuration of aplurality of light patterns described herein (e.g., configurationsillustrated in FIGS. 5A-5F). In some implementations, parabolicreflectors 922 include reflective surfaces 922-1 facing opticallyrecordable medium 826. In FIG. 9H, wide-field beam 834-B is projectedtoward parabolic reflectors 922 (e.g., off-axis) such that beam 834-B isreceived by reflective surfaces 922-1 of parabolic reflectors 922 andreflected by reflective surfaces 922-1 onto optically recordable medium826 as a plurality of light patterns 836 (e.g., in-line). In someembodiments, wide-field beam 834-B is projected by lens 814-2corresponding to lens 814-1 of the second set of optical elements 800-B.

In some implementations, parabolic reflectors 922 project light patterns836 converging on reference plane 902 positioned between opticallyrecordable medium 826 and parabolic reflectors 922, similar to lenses820-1 in FIG. 9A. In some embodiments, reference line 902 corresponds toreference line 410-1 in FIG. 4A.

In some embodiments, parabolic reflectors 922 have identical shapes(e.g., curvature) and sizes (e.g., diameter). For example, in FIG. 9H,parabolic reflector 922-A is identical to parabolic reflector 922-B. Insome embodiments, parabolic reflectors 922 have different shapes andsizes. For example, parabolic reflector 922-A has a curvature differentfrom a curvature of parabolic reflector 922-C in FIG. 9I. In someembodiments, parabolic reflectors are attached to or coupled with eachother, as shown in FIG. 9H. In some embodiments, parabolic reflectorsare separated from each other, as shown in FIG. 9I.

In some embodiments, optical elements 920 including parabolic reflectors922 are used in an illumination configuration using a single-beam. InFIG. 9J, lens 824-1 is configured to provide beam 832-C that istransmitted through recordable medium 826 toward parabolic reflectors922. Beam 832-C is reflected off reflective surfaces 922-1 of parabolicreflectors 922 onto optically recordable medium 826 as a plurality oflight patterns 836 (e.g., in-line). A holographic medium (e.g.,holographic medium 404 described above with respect to FIG. 4A) istherefore created by using a single beam (e.g., beam 832-C)illumination.

FIG. 9K is a schematic diagram illustrating a side view of opticalelements 930 for generating a holographic medium in accordance with someembodiments. Optical elements 930 is similar to the third set of opticalelements 800-C described above with respect to FIG. 8A for providing aplurality of light patterns (e.g., light patterns 932-A and 932-B) ontooptically recordable medium 826 for forming a holographic medium, expectthat optical elements 930 include diffractive optical element (DOE) 934.In some embodiments, optical elements 930 include two or morediffractive optical elements 934. DOE 934 receives beam 834-D. Beam834-D does not need to be a wide-field beam. In some embodiments, beam834-D corresponds to beam 834-A shown in FIG. 8A. DOE 934 projects beam834-D as a plurality of light patterns (e.g., light patterns 932-A and932-B) onto optically recordable medium 826. In some embodiments, DOE934 is configured to provide any configuration of a plurality of lightpatterns described herein (e.g., configurations illustrated in FIGS.5A-5F). In some embodiments, DOE 934 is used to form holographic mediumsdescribed above with respect to FIGS. 4A-4B. In some embodiments, DOE934 is used to form holographic mediums described above with respect toFIG. 4C.

In some embodiments, DOE 934 includes one or more diffractive beamsplitters configured to project an array of spots (e.g., an array oflight patterns including light patterns 932-A and 932-B). In someembodiments, DOE 934 includes one or more diffractive diffusers formodifying the projected light patterns. In some embodiments, DOE 934 isoptically coupled with lens 936 (e.g., lens 936 is a condenser lens),which focuses the plurality of light patterns including light patterns932-A and 932-B. In some embodiments, DOE 934 is coupled with aplurality of lenses, such as lenses 820-1 described above with respectto FIG. 9A. For example, DOE 934 is coupled with lens 820-A configuredto focus light pattern 932-A and with lens 820-B configured to focuslight pattern 932-B. In some embodiments, optical elements 930 furtherinclude diffuser 938 optically coupled with DOE 934 and/or lens 936.Diffuser 938 diffuses light, thereby expanding light patterns 932projected onto optically recordable medium 826. In some embodiments,diffuser 938 is used to reduce or eliminate high (spatial) frequencyvariation in the plurality of light patterns.

FIG. 9L is a schematic diagram illustrating a side view of opticalelements 940 for generating a holographic medium in accordance with someembodiments. Optical elements 940 are similar to the third set ofoptical elements 800-C described above with respect to FIG. 8A forproviding a plurality of light patterns (e.g., light patterns 942) ontooptically recordable medium 826 for forming a holographic medium, expectthat optical elements 940 include optical fibers 944 (e.g., opticalfibers 944-A and 944-B). Each optical fiber (e.g., optical fiber 944-A)is configured to receive a portion of light (e.g., beam 834-A) projectedby light source 802 in FIG. 8A onto input fiber end 948-1 and projectthe beam as a light pattern (e.g., light pattern 942-A) onto opticallyrecordable medium 826 from output fiber end 948-2. In some embodiments,optical fibers 944 are optically coupled to light source 802 through asingle fiber (e.g., a multi-mode fiber). In some embodiments, opticalfibers 944 are optically coupled to light source 802 as bundle 946 ofoptical fibers. In some embodiments, optical fibers 944 are opticallycoupled to beam splitter 810 and optionally to polarizer 814-1 and areconfigured to receive beam 834-A described with respect to FIG. 8A. Insome embodiments, optical fibers 944 are coupled with other opticalelements (e.g., one or more lenses) for receiving beam 834-A. In someembodiments, optical fibers 944 are single-mode optical fibers. In someembodiments, optical fibers 944 are multi-mode optical fibers.

In some embodiments, optical fibers 944 (e.g., output fiber ends 948-2of optical fibers 944) are configured to provide any configuration of aplurality of light patterns described herein (e.g., configurationsillustrated in FIGS. 5A-5F). In some embodiments, optical fibers 944 areused to form holographic mediums described above with respect to FIGS.4A-4B. In some embodiments, optical fibers 944 are used to formholographic mediums described above with respect to FIG. 4C.

In some embodiments, optical fibers 944 are coupled with lenses 950. Insome embodiments, lenses 950 are arranged in a microlens array. In someembodiments, optical fibers 944 are coupled with a single lens (e.g., acondenser lens), such as lens 936 described above with respect to FIG.9K.

In some embodiments, optical fibers 944 are coupled with plurality offilters 952 (e.g., color filters). In some embodiments, filters 952 areconfigured to modify a wavelength (e.g., color) of light patterns 942provided by optical fibers 944. In some embodiments, optical fibers 944are optically coupled with one or more attenuators, such as attenuators904-A and 904-B described above with respect to FIG. 9A.

In light of these principles, we now turn to certain embodiments.

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source (e.g., light source802 provides beam 830 in FIG. 8A) and separating the light into a firstportion of the light and a second portion of the light that is spatiallyseparated from the first portion of the light (e.g., beam splitter 810separates beam 830 into beam 832-A and 834-A). The method also includestransmitting the first portion of the light through a first set ofoptical elements (e.g., the first set of optical elements 800-A) toprovide a first wide-field beam (e.g., beam 832-B), transmitting thesecond portion of the light through a second set of optical elements(e.g., the second set of optical elements 800-B) to provide a secondwide-field beam (e.g., beam 834-B) that is spatially separated from thefirst wide-field beam, and transmitting the second wide-field beamthrough a third set of optical elements (e.g., the third set of opticalelements 800-C) to provide a plurality of separate light patterns (e.g.,light patterns 836). The method further includes concurrently projectingthe first wide-field beam and the plurality of separate light patternsonto an optically recordable medium to form a holographic medium (e.g.,beam 832-B and light patterns 836 are concurrently projected onoptically recordable medium 826 to form a holographic medium). In someembodiments, the light is coherent light, such as a laser beam.

In some embodiments, the first wide-field beam is projected onto theoptically recordable medium through a first surface of the opticallyrecordable medium (e.g., beam 832-B is projected onto surface 826-1 ofoptically recordable medium 826 in FIG. 8A) and the plurality ofseparate light patterns is projected onto the optically recordablemedium through a second surface of the optically recordable medium thatis opposite to the first surface of the optically recordable medium(e.g., light patterns 836 are projected onto surface 826-2 of opticallyrecordable medium 826).

In some embodiments, the first wide-field beam and the plurality ofseparate light patterns are projected onto the optically recordablemedium through a first surface of the optically recordable medium (e.g.,beam 832-B and light patterns 836 are projected onto surface 826-2 ofoptically recordable medium 826 in FIG. 8B).

In some embodiments, the first set of optical elements is located awayfrom an optical axis of the holographic medium (e.g., the first set ofoptical elements 800-A is located away from an optical axis of opticallyrecordable medium 826 forming the holographic medium, as shown in FIG.8A), and projecting the first wide-field beam onto the opticallyrecordable medium to form the holographic medium includes projecting thefirst wide-field beam onto the holographic medium at a first angle(e.g., beam 832-B is projected onto holographic medium 826 at Angle A′as shown in Section A of FIG. 8C).

In some embodiments, at least a subset of the second set of opticalelements is located to intersect with an optical axis of the holographicmedium (e.g., parabolic reflector 816 of the second set of opticalelements 800-B is located or positioned to intersect with an opticalaxis of optically recordable medium 826 that forms the holographicmedium), and projecting the second wide-field beam onto the opticallyrecordable medium to form the holographic medium includes projecting thesecond wide-field beam onto the holographic medium at a second anglethat is distinct from the first angle (e.g., beam 832-B and beam 834-Bare projected onto optically recordable medium 826 at different anglesas shown in FIG. 8A). For example, in some implementations, the firstwide-field beam is projected onto the holographic medium at an off-axisangle (e.g., 45 degrees) and the second wide-field beam is projectedonto the holographic medium at an on-axis angle (e.g., a projectionangle of 0 degree).

In some embodiments, the first set of optical elements includes a firstlens (e.g., lens 824-1 in FIG. 8A) and the second set of opticalelements includes a second lens (e.g., lens 814-1) that is distinct andseparate from the first lens. In some embodiments, lenses 824-1 and814-1 are microscopic objectives.

In some embodiments, the second set of optical elements includes aparabolic reflector (e.g., parabolic reflector 816 in FIG. 8A) opticallycoupled with the second lens (e.g., lens 814-1), and transmitting thesecond portion of the light through the second set of optical elementsincludes, with the parabolic reflector, receiving the first portion ofthe light (e.g., parabolic reflector 816 receives beam 834-A) andcollimating the first portion of the light to provide the secondwide-field beam (e.g., parabolic reflector 816 collimates beam 834-A andprovides wide-field beam 834-B).

In some embodiments, the third set of optical elements includes aplurality of lenses (e.g., the third set of optical elements 800-Cincludes lenses 820 in FIG. 8A). In some embodiments, the plurality oflenses includes a first pattern lens and a second pattern lens distinctand separate from the first pattern lens (e.g., lenses 820-A and 820-Bin FIG. 9A). The method includes projecting, with the first patternlens, a first portion of the plurality of separate light patterns ontothe optically recordable medium (e.g., projecting light pattern 836-Awith lens 820-A onto optically recordable medium 826), and projecting,with the second pattern lens, a second portion of the plurality ofseparate light patterns onto the optically recordable medium (e.g.,projecting light pattern 836-B with lens 820-B onto optically recordablemedium 826).

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light, and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light (e.g., light source 802 and beam splitter810 in FIG. 8A). The system also includes (i) a first set of opticalelements (e.g., the first set of optical elements 800-A) configured totransmit the first portion of the light for providing a first wide-fieldbeam, (ii) a second set of optical elements (e.g., the second set ofoptical elements 800-B) configured to transmit the second portion of thelight for providing a second wide-field beam, and (iii) a third set ofoptical elements (e.g., the third set of optical elements 800-C)optically coupled with the second set of optical elements and configuredto transmit the second wide-field beam for providing a plurality ofseparate light patterns onto an optically recordable medium for formingthe holographic medium.

In some embodiments, the first set of optical elements is configured toproject the first wide-field beam onto the optically recordable mediumthrough a first surface of the optically recordable medium (e.g.,surface 826-1 in FIG. 8A). The second set of optical elements and thethird set of optical elements are configured to project the plurality ofseparate light patterns onto the optically recordable medium through asecond surface of the optically recordable medium that is opposite tothe first surface of the optically recordable medium (e.g., surface826-2 in FIG. 8A).

In some embodiments, the first set of optical elements, the second setof optical elements, and the third set of optical elements areconfigured to project the first wide-field beam and the plurality ofseparate light patterns onto the optically recordable medium through afirst surface of the optically recordable medium (e.g., surface 826-2 inFIG. 8B).

In some embodiments, the first set of optical elements is located awayfrom an optical axis of the holographic medium (e.g., an axis that isperpendicular to the holographic medium), and projecting the firstwide-field beam onto the optically recordable medium to form theholographic medium includes projecting the first wide-field beam ontothe holographic medium at a first angle (e.g., FIG. 8A).

In some embodiments, at least a subset of the second set of opticalelements is located to intersect with an optical axis of the holographicmedium, and projecting the second wide-field beam onto the opticallyrecordable medium to form the holographic medium includes projecting thesecond wide-field beam onto the holographic medium at a second anglethat is distinct from the first angle (e.g., FIG. 8A).

In some embodiments, the first set of optical elements includes a firstlens (e.g., lens 824-1 in FIG. 8A) and the second set of opticalelements includes a second lens that is distinct and separate from thefirst lens (e.g., lens 814-1 in FIG. 8A). In some embodiments, the firstlens is a first objective (e.g., a microscope objective). In someembodiments, the second lens is a second objective (e.g., a microscopeobjective). In some embodiments, the first objective is coupled with anaperture (e.g., aperture 828-1 in FIG. 8A).

In some embodiments, the first set of optical elements includes anadjustable reflector configured to direct the first portion of the lighttoward the first lens (e.g., reflector 822-1 in FIG. 8A). In someembodiments, an angular position of the adjustable reflector is selectedaccording to the angle for projecting the eye tracking light from thelight source in a head-mounted display device. For example, in FIG. 8C,the angle at which beam 832-B is transmitted toward optically recordablemedium 826 (e.g., Angle A′) is adjusted to correspond to the angle atwhich beam 402-1 is projected toward holographic medium 404 (e.g., AngleA″) in holographic illuminator 400.

In some embodiments, the second set of optical elements includes aparabolic reflector optically coupled with the second lens andconfigured to collimate the first portion of the light to provide thesecond wide-field beam (e.g., parabolic reflector 816 in FIG. 8A). Insome embodiments, the parabolic reflector is positioned at a 45-degreeangle with respect to the direction of the second portion of the light.In some embodiments, the parabolic reflector is configured to providethe second wide-field beam having a diameter of at least 100 mm (e.g.,beam 834-B has a diameter of at least 100 mm).

In some embodiments, the third set of optical elements includes aplurality of lenses (e.g., lenses 820 in FIG. 8A). In some embodiments,the plurality of lenses is arranged in a circular configuration (e.g.,lenses 820-3 are arranged in a circular configuration in FIG. 9C).

In some embodiments, the beam splitter is a polarizing beam splitter(e.g., beam splitter 810 in FIG. 8A) configured to separate the lightinto the first portion of the light having a first polarization (e.g.,beam 832-A has a first polarization, such as a horizontal polarization)and the second portion of the light having a second polarization (e.g.,beam 834-A has a second polarization, such as a vertical polarization)that is distinct from the first polarization. In some embodiments, thelight source is a laser (e.g., light source 802 is a laser). In someembodiments, the light source is coupled with a polarizer (e.g.,polarizer 808). In some embodiments, the light source is coupled with abeam expander (e.g., beam expander 804) and an aperture (e.g., aperture806).

In some embodiments, the first set of optical elements includes apolarizer for adjusting a polarization of the first portion of the lightand/or the second set of optical elements includes a polarizer (e.g., ahalf-wave plate) for adjusting a polarization of the second portion ofthe light. For example, polarizer 812 (e.g., a half-wave plate) adjuststhe polarization of beam 834-A in FIG. 8A.

In accordance with some embodiments, a holographic medium is made by anyof the methods described herein (e.g., holographic medium 404 in FIG.4A).

In accordance with some embodiments, an eye tracker includes a lightsource (e.g., light source 402 in FIG. 6A), the holographic medium(e.g., holographic medium 404) optically coupled with the light sourceand a detector (e.g., detector 602). The holographic medium isconfigured to receive light (e.g., light 402-1) provided from the lightsource and project a plurality of separate light patterns (e.g., lightpatterns 406-1, 406-2, and 406-3) concurrently toward an eye. In someembodiments, a respective pattern of the plurality of separate lightpatterns is a spot (e.g., a circular spot, a rectangular spot, etc. asshown in FIGS. 5A, 5C, and 5D). In some embodiments, a respectivepattern of the plurality of separate light pattern is a line (e.g., astraight line as shown in FIG. 5B or a curved line).

The detector is configured to detect a reflection (e.g., an image of anarea defined by rays 608-1) of at least a subset of the plurality ofseparate light patterns, reflected off the eye, for determining alocation of a pupil of the eye (e.g., eye 408).

In accordance with some embodiments, a head-mounted display deviceincludes one or more optical elements (e.g., one or more lenses), one ormore displays configured to project light through or off of the one ormore optical elements toward an eye of a wearer of the head-mounteddisplay device, and the eye tracker described herein (e.g., displaydevice 600 in FIG. 6A). In some embodiments, the one or more opticalelements include one or more combiners (e.g., combiner 644 in FIG. 6D).

In accordance with some embodiments, an eye-tracking system includes aholographic illuminator that includes a light source configured toprovide light and a holographic medium optically coupled with the lightsource (e.g., holographic illuminator 400 includes light source 402 andholographic medium 404 as shown in FIG. 4A). The holographic medium isconfigured to receive the light provided from the light source (e.g.,light 402-1) and project a plurality of separate light patternsconcurrently toward an eye (e.g., light patterns 406-1, 406-2, and 406-3are projected toward eye 408). The eye-tracking system also includes adetector configured to detect a reflection of at least a subset of theplurality of separate light patterns, reflected off the eye, fordetermining a location of a pupil of the eye (e.g., detector 602 in FIG.6A).

In some embodiments, the holographic medium is configured to transmit aconcurrent projection of the plurality of separate light patterns (e.g.,light patterns 406-1, 406-2, and 406-3). In some embodiments, theresultant glints (e.g., reflections) have identifiable signatures, suchas location, intensity, and shape, for eye tracking (e.g., FIG. 7Billustrates a plurality of separate glints with identifiablesignatures).

In some embodiments, the light source is a single-point light source(e.g., light source 402 in FIG. 4A is a single-point light source). Insome embodiments, the light source is a wide-field light source. In someembodiments, the light projected by the light source is collimated.

In some embodiments, the light source is located away from an opticalaxis of the holographic medium (e.g., light source 402 is located awayfrom an optical axis of holographic medium 404 in FIG. 4A). In someembodiments, the light source is on the optical axis of the holographicmedium.

In some embodiments, the holographic medium is a reflection holographicmedium configured to receive the light from the light source on a firstsurface of the holographic medium (e.g., surface 404-2 of holographicmedium 404 in FIG. 4A) and concurrently project (e.g., reflect,diffract, etc.) the plurality of separate light patterns through thefirst surface of the holographic medium.

In some embodiments, the holographic medium is a transmissionholographic medium configured to receive the light from the light sourceon a first surface of the holographic medium (e.g., surface 404-1 ofholographic medium 404 in FIG. 4C) and concurrently project (e.g.,transmit, diffract, etc.) the plurality of separate light patternsthrough a second surface of the holographic medium (e.g., surface 404-2of holographic medium 404) that is opposite to the first surface of theholographic medium.

In some embodiments, the plurality of separate light patterns includes afirst light pattern (e.g., light pattern 406-1 in FIG. 4D) and a secondlight pattern distinct and separate from the first light pattern (e.g.,light pattern 406-2). The first light pattern of the plurality ofseparate light patterns is projected toward the eye at a first angle(e.g., the angle defined by reference line 442 and reference line 440)and the second light pattern of the plurality of separate light patternsis projected toward the eye at a second angle (e.g., the angle definedby reference line 444 and reference line 440) distinct from the firstangle. In some embodiments, the first light pattern and the second lightpattern have the same shape when projected on the eye. In someembodiments, the first light pattern and the second light pattern havedifferent shapes when projected on the eye.

In some embodiments, the plurality of separate light patterns isarranged in a circular configuration (e.g., in FIG. 5A, configuration502 includes light patterns 502-1, 502-2, and 502-3 arranged in acircular configuration). In some embodiments, the circular configurationincludes a plurality of separate spots along a periphery of a referencecircle. In some embodiments, the plurality of separate light patterns isarranged in a striped, rectangular, sinusoidal, crossed, or non-uniformconfiguration (e.g., FIG. 5B).

In some embodiments, the plurality of separate light patterns arrangedin the circular configuration is configured to illuminate an area with adiameter of at least 10 mm on a surface of the eye. For example, lightpatterns 704 in Section A of FIG. 7B span over an area with a diameterof at least 10 mm on a surface of an eye.

In some embodiments, the plurality of separate light patterns isarranged in a distorted configuration (e.g., a non-rectangular andnon-circular configuration, such as a pincushion configuration) thatcounters for a contoured surface of the eye so that the at least asubset of the plurality of separate light patterns reflected off thecontoured surface of the eye is arranged in a non-distortedconfiguration. For example, FIG. 7B illustrates that reflection of theplurality of light patterns arranged in the pincushion configuration (asshown in section A of FIG. 7B) off one or more surfaces of an eye is ina substantially non-distorted configuration, such as a rectangularconfiguration (as shown in section B of FIG. 7B).

In some embodiments, the holographic medium is configured to project theplurality of separate light patterns concurrently so that each lightpattern of the plurality of separate light patterns converges inproximity to a surface of the eye (e.g., light patterns 406-1, 406-2,and 406-3 converge on a reference plane 410-1 in FIG. 4A). In someimplementations, the convergence points create a plurality of virtualsingle-point light sources near the surface of the eye.

In some embodiments, the holographic medium is coupled with a waveguideto receive the light provided from the light source and propagatedthrough the waveguide (e.g., holographic medium 454 is coupled withwaveguide 456 to receive light 402-1 in FIG. 4E). In some embodiments,the light propagates through the waveguide in a direction that is notparallel to the optical axis of the holographic medium (e.g., light402-2 propagates in a direction not parallel to optical axis ofholographic medium 454). In some embodiments, projecting, by theholographic medium, the plurality of separate light patternsconcurrently toward the eye includes directing toward the eye at least aportion of the light propagated through the waveguide as the pluralityof separate light patterns (e.g., light patterns 454-1 and 454-2). Insome embodiments, the waveguide includes, or is coupled with, anin-coupling element (e.g., a prism or a diffractive or holographicstructure), which is configured to in-couple the light into thewaveguide in order to reach angles of total internal reflection (e.g.,in-coupling device 452).

In accordance with some embodiments, a head-mounted display deviceincludes one or more optical elements (e.g., one or more lenses 608),one or more displays (e.g., display 610 in FIG. 6A) configured toproject light through the one or more lenses, and the eye-trackingsystem described herein (e.g., an eye-tracking system including detector602, light source 402, and holographic medium 404). In some embodiments,the head-mounted display device renders augmented reality images (e.g.,display device 640 renders augmented reality images as shown in FIG.6D). In some embodiments, the head-mounted display device rendersvirtual reality images (e.g., display device 600 renders virtual realityimages as shown in FIG. 6A).

In some embodiments, the holographic medium of the eye-tracking systemis positioned adjacent to the one or more optical elements (e.g., inFIG. 6A, holographic medium 404 is positioned adjacent to one or morelenses 608).

In some embodiments, the light source of the eye-tracking system ispositioned away from the one or more optical elements so that the lightsource does not occlude the one or more displays (e.g., in FIG. 6A,light source 402 is positioned away from one or more lenses 608). Insome embodiments, the light source of the eye-tracking system ispositioned off-axis from the one or more lenses (e.g., the light sourceof the eye-tracking system is positioned away from an optical axis ofthe one or more lenses). In some embodiments, the light source of theeye-tracking system is positioned so that the light source does notocclude the field of view provided by the one or more lenses and the oneor more displays.

In some embodiments, the detector of the eye-tracking system ispositioned away from the one or more optical elements so that thedetector does not occlude the one or more displays. In some embodiments,the detector of the eye-tracking system is positioned off-axis from theone or more lenses. In some embodiments, the detector is positioned sothat the light source does not occlude the field of view provided by theone or more lenses and the one or more displays.

In some embodiments, the eye-tracking system is configured to determinea location of a pupil of a first eye and the device includes a secondeye-tracking system, that is distinct and separate from the eye-trackingsystem, configured to determine a location of a pupil of a second eyethat is distinct from the first eye (e.g., in FIG. 6C, device 630includes display device 600-A with a first eye-tracking system for eye408-A and display device 600-B with a second eye-tracking system for eye408-B).

In some embodiments, the device includes a combiner (e.g., combiner 644in FIG. 6D) configured to combine the light from the one or moredisplays (e.g., light 642-1 from display 642) and light from an outsideof the head-mounted display device (e.g., light 650) for providing anoverlap of an image rendered by the light from the one or more displaysand a real image that corresponds to the light from the outside of thehead-mounted display device.

In accordance with some embodiments, a method for determining a locationof a pupil of an eye includes providing light with a light source (e.g.,light 402-1 provided by light source 402 in FIG. 6A), receiving, with aholographic medium (e.g., holographic medium 404 receives light 402-1)optically coupled with the light source, the light provided by the lightsource, and projecting, with the holographic medium, a plurality ofseparate light patterns concurrently toward an eye (e.g., holographicmedium 404 projects light patterns 406-1, 406-2, and 406-3 toward eye408). The method also includes detecting, with a detector, a reflectionof at least a subset of the plurality of separate light patternsreflected off the eye of the wearer (e.g., detector 602 captures animage of at least a subset of light patterns 406-1, 406-2, and 406-3reflected off a surface of eye 408). The method further includesdetermining, based on the reflection of at least the subset of theplurality of separate light patterns reflected off the eye, a locationof a pupil of the eye. For example, as shown in Section B of FIG. 7A, inaccordance with a determination that reflection of all of the pluralityof separate light patterns is detected, it is determined that the pupilof the eye is located in a center position (also called a neutralposition). In another example, as shown in Section A of FIG. 7A, inaccordance with a determination that reflection of one or more lightpatterns of the plurality of separate light patterns is not detected ordetected at a lower intensity, it is determined that the pupil of theeye is tilted (e.g., toward the one or more light patterns of theplurality of separate light patterns).

In some embodiments, determining the location of the pupil of the eyeincludes determining respective locations of at least the subset of theplurality of separate light patterns in the reflection (e.g.,determining whether one or more glints are not detected, and/or whichglints are not detected).

In some embodiments, determining the location of the pupil of the eyeincludes determining respective intensities of the plurality of separatelight patterns in the reflection (e.g., determining whether one or moreglints are detected at a lower intensity, such as an intensity below apredefined intensity threshold, and/or which glints are detected at alower intensity).

In some embodiments, determining the location of the pupil of the eyeincludes determining a respective configuration of the plurality ofseparate light patterns in the reflection (e.g., determining theconfiguration of glints 706 in Section B of FIG. 7B).

In some implementations, a respective light pattern of the plurality ofseparate light patterns has a distinct combination of opticalcharacteristics (e.g., color, shape, size, intensity, etc.). As aresult, each light pattern is identifiable based on the combination ofoptical characteristics.

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light and a beamsplitter configured to separate the light into a first portion of thelight (e.g., beam 832-A in FIG. 8A) and a second portion of the light(e.g., beam 834-A in FIG. 8A) that is spatially separated from the firstportion of the light. The system also includes a first set of opticalelements (e.g., the first set of optical elements 800-A) configured totransmit the first portion of the light for providing a first wide-fieldbeam onto an optically recordable medium (e.g., optically recordablemedium 826 in FIG. 8A), a second set of optical elements (e.g., thesecond set of optical elements 800-B) configured to transmit the secondportion of the light through for providing a second wide-field beam, anda plurality of lenses (e.g., lenses 820) optically coupled with thesecond set of optical elements configured to receive the secondwide-field beam (e.g., beam 834-B) and project a plurality of separatelight patterns (e.g., light patterns 836) onto the optically recordablemedium (e.g., optically recordable medium 826) for forming theholographic medium.

In some embodiments, the plurality of lenses is arranged in a microlensarray (e.g., in FIG. 9A, lenses 820 are arranged in a microlens array).

In some embodiments, the plurality of lenses is arranged in a circularconfiguration (e.g., lenses 820-3 are arranged in a circularconfiguration as shown in FIG. 9C). In some embodiments, the pluralityof lenses includes seven or more lenses (e.g., between 7 and 20 lenses).

In some embodiments, the plurality of lenses is arranged in arectangular configuration (e.g., lenses 820-2 are arranged in arectangular configuration in FIG. 9B). In some embodiments, theplurality of lenses includes at least 20 lenses (e.g., between 20 and1000 lenses).

In some embodiments, the plurality of lenses is positioned adjacent tothe optically recordable medium (e.g., lenses 820 are adjacent tooptically recordable medium 826 in FIG. 9A). In some embodiments, theplurality of lenses is positioned within 25 mm from the opticallyrecordable medium. In some embodiments, the plurality of lenses ispositioned within 10 mm from the optically recordable medium. In someembodiments, the plurality of lenses is positioned within 5 mm from theoptically recordable medium.

In some embodiments, the system includes a condenser lens that isdistinct from the plurality of lenses and optically coupled with theplurality of lenses (e.g., condenser lens 818 is optically coupled withlenses 820 in FIG. 9A). In some embodiments, the diameter of thecondenser lens is at least 75 mm. In some embodiments, each lens of theplurality of lenses is configured to direct the second wide-field beamtoward a reference pupil. For example, lens 818 directs beam 834-Btoward reference pupil 903 in FIG. 9A. In some implementations, theposition of reference pupil 903 corresponds to a position of eye 408 inFIG. 4A (e.g., an eye of a user of a display device, such as displaydevice 600 in FIG. 6A).

In some embodiments, each lens of the plurality of lenses is configuredto focus a respective portion of the second wide-field beam on areference focal plane. The reference focal plane is located between theoptically recordable medium and the reference pupil. As a result, whenholographic medium 404 formed using the optically recordable medium isilluminated with light from light source 402 as shown in FIG. 4A, theholographic medium projects light toward reference focal plane 410-1that is located between holographic medium 404 and the pupil of eye 408.

In some embodiments, the plurality of lenses includes a first lensconfigured to project a first light pattern of the plurality of separatelight patterns onto the optically recordable medium at a first angle(e.g., lens 820-A projects light pattern 836-A onto optically recordablemedium 826 at a first angle in FIG. 9A), and a second lens configured toproject a second light pattern of the plurality of separate lightpatterns onto the optically recordable medium at a second angle that isdistinct from the first angle (e.g., lens 820-B projects light pattern836-B onto optically recordable medium 826 at a second angle in FIG.9A). In some embodiments, the first angle is 45 degrees with respect toan optical axis of the holographic medium (e.g., an optical axis that isperpendicular to the holographic medium). In some embodiments, thesecond angle is 0 degrees with respect to the optical axis of theholographic medium.

In some embodiments, the system includes a plurality of attenuatorsoptically coupled with the plurality of lenses and configured toattenuate intensity of light provided to respective lenses of theplurality of lenses (e.g., attenuators 904-A and 904-B in FIG. 9A).

In some embodiments, the plurality of attenuators includes a firstattenuator optically coupled with a first lens of the plurality oflenses (e.g., attenuator 836-A optically coupled with lens 820-A in FIG.9A) and configured to attenuate intensity of light (e.g., light pattern836-A) provided to the first lens by a first attenuation factor (e.g.,10% attenuation or no attenuation) and a second attenuator opticallycoupled with a second lens (e.g., attenuator 836-B optically coupledwith lens 820-B), that is distinct from the first lens, of the pluralityof lenses and configured to attenuate intensity of light (e.g., lightpattern 736-B) provided to the second lens by a second attenuationfactor (e.g., 20% attenuation) that is distinct from the firstattenuation factor.

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source and separating thelight into a first portion of the light and a second portion of thelight that is spatially separated from the first portion of the light.The method also includes transmitting the first portion of the lightthrough a first set of optical elements to provide a first wide-fieldbeam, transmitting the second portion of the light through a second setof optical elements to provide a second wide-field beam that isspatially separated from the first wide-field beam onto an opticallyrecordable medium, and transmitting the second wide-field beam through aplurality of lenses to provide a plurality of separate light patterns.The method further includes concurrently projecting the first wide-fieldbeam and the plurality of separate light patterns onto the opticallyrecordable medium to form the holographic medium.

In some embodiments, the plurality of lenses is arranged in a microlensarray.

In some embodiments, the method includes projecting the plurality ofseparate light patterns arranged in a circular configuration (e.g., FIG.9C).

In some embodiments, the method includes projecting the plurality ofseparate light patterns arranged in a rectangular configuration (e.g.,FIG. 9B).

In some embodiments, the method includes focusing the second wide-fieldbeam onto a focal plane that is adjacent to the optically recordablemedium (e.g., in FIG. 9A, lenses 820-1 focus light patterns 836 ontoreference plane 902 adjacent to optically recordable medium 826). Insome embodiments, the reference focal plane corresponds to a focal planelocated between the holographic medium and an eye of a user of an eyetracker (e.g., reference plane 410-1 located between holographic medium404 and eye 408 in FIG. 4A).

In some embodiments, the method includes transmitting the secondwide-field beam (e.g., beam 834-B in FIG. 9A) through a condenser lens(e.g., lens 818) that is distinct from the plurality of lenses prior totransmitting the second wide-field beam through the plurality of lenses(e.g., lenses 820). In some embodiments, the condenser lens isconfigured to direct the second wide-field beam toward a reference pupil(e.g., reference pupil 903).

In some embodiments, the method includes focusing, with each lens of theplurality of lenses, a respective portion of the second wide-field beamon a reference focal plane (e.g., FIG. 9A). The reference focal plane islocated between the optically recordable medium and the reference pupil.In some embodiments, the reference focal plane corresponds to a focalplane located between the holographic medium and an eye of a user of aneye tracker (e.g., FIG. 4A).

In some embodiments, the method includes projecting, with a first lensof the plurality of lenses, a first light pattern of the plurality ofseparate light patterns onto the optically recordable medium at a firstangle, and projecting, with a second lens of the plurality of lenses, asecond light pattern of the plurality of separate light patterns ontothe optically recordable medium at a second angle that is distinct fromthe first angle (e.g., FIG. 9A). In some embodiments, the first angle is55 degrees with respect to an optical axis of the holographic medium(e.g., an optical axis that is perpendicular to the holographic medium),and the second angle is 0 degrees.

In some embodiments, the method includes attenuating, with a firstattenuator optically coupled with a first lens of the plurality oflenses, intensity of light provided to the first lens by a firstattenuation factor (e.g., 10% attenuation or no attenuation) andattenuating, with a second attenuator optically coupled with a secondlens, that is distinct from the first lens, of the plurality of lenses,intensity of light provided to the second lens by a second attenuationfactor (e.g., 20% attenuation) that is distinct from the firstattenuation factor (e.g., FIG. 9A).

In accordance with some embodiments, a holographic medium is made by themethod described herein (e.g., holographic medium 404 in FIG. 4A).

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light, and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light. The system also includes a first set ofoptical elements (e.g., the first set of optical elements 800-A in FIG.8A) configured to transmit the first portion of the light for providinga first wide-field beam onto an optically recordable medium, a secondset of optical elements (e.g., the second set of optical elements 800-B)configured to transmit the second portion of the light for providing asecond wide-field beam, and a plurality of prisms (e.g., prisms 912 inFIG. 9E) optically coupled with the second set of optical elements andconfigured to receive the second wide-field beam (e.g., beam 834-B) andproject a plurality of separate light patterns onto the opticallyrecordable medium for forming the holographic medium (e.g., lightpatterns 836 are projected by prisms 912 onto optically recordablemedium 826 in FIG. 9G).

In some embodiments, the plurality of prisms is arranged in a circularconfiguration (e.g., prisms 912 in FIG. 9E are arranged in a circularconfiguration illustrated in FIG. 9C).

In some embodiments, the plurality of prisms is arranged in arectangular configuration (e.g., prisms 912 in FIG. 9E are arranged in arectangular configuration illustrated in FIG. 9B).

In some embodiments, the plurality of prisms is positioned adjacent tothe optically recordable medium (e.g., prisms 912 are positionedadjacent to optically recordable medium 826 in FIG. 9E).

In some embodiments, the system includes a plurality of lenses that isoptically coupled with the plurality of prisms (e.g., lenses 921 areoptically coupled with prisms 912 in FIG. 9E). For example, the systemincludes a first lens that is optically coupled with a first prism ofthe plurality of prisms (e.g., lens 921-A is optically coupled withprism 912-A), and a second lens that is distinct from the first lens andoptically coupled with a second prism of the plurality of prisms that isdistinct and separate from the first prism (e.g., lens 921-B isoptically coupled with prism 912-B). In some embodiments, the pluralityof lenses is arranged in a microlens array.

In some embodiments, each lens of the plurality of lenses is configuredto focus a respective portion of the second wide-field beam on areference focal plane, and the reference focal plane is located betweenthe optically recordable medium and a reference pupil (e.g., lenses 921focus light patterns 836 on reference plane 902 in FIG. 9G).

In some embodiments, the plurality of prisms includes a first prismconfigured to project a first light pattern of the plurality of separatelight patterns onto the optically recordable medium at a first angle,and a second prism configured to project a second light pattern of theplurality of separate light patterns onto the optically recordablemedium at a second angle that is distinct from the first angle (e.g.,FIG. 9G).

In some embodiments, the first prism is located at a first distance fromthe optically recordable medium (e.g., distance D1 in FIG. 9E) and thesecond prism is located at a second distance from the opticallyrecordable medium (e.g., distance D2). The second distance is distinctfrom the first distance (e.g., distance D2 is greater than distance D1).

In some embodiments, the plurality of prisms is arranged in a domeconfiguration (e.g., prisms 912 are arranged in a dome configuration asshown in FIG. 9F). In some embodiments, the plurality of prisms isarranged in a dome configuration (e.g., 12 prisms are arranged inconcentric circles, where 4 prisms are arranged to form an inner circleand 8 prisms are arranged to form an outer circle). In someimplementations, the outermost prisms direct light onto the opticallyrecordable medium at a 45-degree angle. The angle is defined withrespect to an optical axis of the optically recordable medium (e.g.,directions of light patterns 836 in FIG. 9G correspond to the directionsof light patterns 406-1 and 406-2 in FIG. 4D).

In some embodiments, the system includes a plurality of attenuatorsoptically coupled with the plurality of prisms and configured toattenuate intensity of light provided by respective prisms of theplurality of prisms (e.g., attenuators 904-A and 904-B described withrespect to FIG. 9A are coupled with prisms 912 in FIG. 9E).

In some embodiments, the plurality of attenuators includes a firstattenuator (e.g., attenuator 904-A in FIG. 9A) optically coupled with afirst prism of the plurality of prisms (e.g., prism 912-A in FIG. 9E)and configured to attenuate intensity of light provided by the firstprism by a first attenuation factor and a second attenuator (e.g.,attenuator 904-B in FIG. 9A) optically coupled with a second prism(e.g., prism 912-B), that is distinct from the first prism, of theplurality of prisms and configured to attenuate intensity of lightprovided by the second prism by a second attenuation factor that isdistinct from the first attenuation factor.

In some embodiments, the system includes a condenser lens coupled withthe plurality of prisms (e.g., condenser lens 818 described with respectto FIG. 9A is coupled with prisms 912 shown in FIG. 9E).

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source, and separating thelight into a first portion of the light and a second portion of thelight that is spatially separated from the first portion of the light(e.g., FIG. 8A). The method also includes transmitting the first portionof the light through a first set of optical elements to provide a firstwide-field beam (e.g., FIG. 8A), transmitting the second portion of thelight through a second set of optical elements to provide a secondwide-field beam that is spatially separated from the first wide-fieldbeam onto an optically recordable medium (e.g., FIG. 8A), andtransmitting the second wide-field beam through a plurality of prisms toprovide a plurality of separate light patterns (e.g., FIG. 9G). Themethod further includes concurrently projecting the first wide-fieldbeam and the plurality of separate light patterns onto the opticallyrecordable medium to form the holographic medium.

In some embodiments, the plurality of prisms is optically coupled with aplurality of lenses (e.g., FIG. 9G).

In some embodiments, the method includes transmitting the secondwide-field beam through the plurality of lenses (e.g., FIG. 9G).

In some embodiments, in some embodiments, the plurality of lenses isconfigured to direct the second wide-field beam toward a reference pupil(e.g., analogous to the configuration shown in FIG. 9A).

In some embodiments, the method includes focusing, with each lens of theplurality of lenses, a respective portion of the second wide-field beamon a reference focal plane, the reference focal plane located betweenthe optically recordable medium and the plurality of lenses. Forexample, the reference focal plane is located between the holographicmedium and an eye of a user of an eye tracker (e.g., analogous to theconfiguration shown in FIG. 9A).

In some embodiments, the method includes projecting, with a first prismof the plurality of prisms, a first light pattern of the plurality ofseparate light patterns onto the optically recordable medium at a firstangle, and projecting, with a second prism of the plurality of prisms, asecond light pattern of the plurality of separate light patterns ontothe optically recordable medium at a second angle that is distinct fromthe first angle (e.g., FIG. 9G). For example, the first angle is 45degrees with respect to an optical axis of the holographic medium (e.g.,an optical axis that is perpendicular to the holographic medium) and thesecond angle is 30 degrees with respect to the optical axis of theholographic medium.

In some embodiments, the first prism is located at a first distance fromthe optically recordable medium and the second prism is located at asecond distance from the optically recordable medium, the seconddistance being distinct from the first distance (e.g., FIG. 9E).

In some embodiments, the method includes projecting the plurality ofseparate light patterns arranged in a circular configuration (e.g.,prisms 912 in FIG. 9E are arranged in a circular configurationillustrated in FIG. 9C for projecting light patterns arranged in acircular configuration).

In accordance with some embodiments, a holographic medium is made by themethod described herein (e.g., holographic medium 404 in FIG. 4A).

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light (e.g., FIG. 8A). The system also includesa first set of optical elements configured to transmit the first portionof the light for providing a first wide-field beam onto an opticallyrecordable medium (e.g., FIG. 8A), a second set of optical elementsconfigured to transmit the second portion of the light for providing asecond wide-field beam (e.g., FIG. 8A), and a plurality of parabolicreflectors (e.g., parabolic reflectors 922 in FIG. 9H) optically coupledwith the second set of optical elements and configured to receive thesecond wide-field beam (e.g., beam 834-B in FIG. 9H) and project aplurality of separate light patterns (e.g., light patterns 836) onto theoptically recordable medium (e.g., optically recordable medium 826) forforming the holographic medium.

In some embodiments, the plurality of parabolic reflectors is arrangedin a circular configuration (e.g., parabolic reflectors 922 in FIG. 9Hare arranged in a circular configuration illustrated in FIG. 9C). Insome embodiments, the plurality of parabolic reflectors includes sevenor more parabolic reflectors (e.g., between 7 and 20 parabolicreflectors).

In some embodiments, the plurality of parabolic reflectors is arrangedin a rectangular configuration (e.g., parabolic reflectors 922 in FIG.9H are arranged in a rectangular configuration illustrated in FIG. 9B).In some embodiments, the plurality of parabolic reflectors includes atleast 20 parabolic reflectors (e.g., between 20 and 1000 parabolicreflectors).

In some embodiments, each parabolic reflector of the plurality ofparabolic reflectors is configured to focus a respective portion of thesecond wide-field beam on a reference focal plane (e.g., parabolicreflectors 922 focus light patterns 836 on reference plane 902 in FIG.9H).

In some embodiments, the reference focal plane is located between theoptically recordable medium and a reference pupil. For example, thereference focal plane is located between the holographic medium and aneye of a user of an eye tracker (e.g., reference plane 410-1 locatedbetween holographic medium 404 and eye 408 in FIG. 4A). In someembodiments, the reference focal plane is located on one side of theoptically recordable medium that is opposite to the plurality ofparabolic reflectors. For example, the optically recordable medium islocated between the plurality of parabolic reflectors and the referencefocal plane.

In some embodiments, the plurality of parabolic reflectors includes afirst parabolic reflector configured to project a first light pattern ofthe plurality of separate light patterns onto the optically recordablemedium at a first angle (e.g., parabolic reflector 922-A projects lightpattern 836-A at a first angle in FIG. 9H), and a second parabolicreflector configured to project a second light pattern of the pluralityof separate light patterns onto the optically recordable medium at asecond angle that is distinct from the first angle (e.g., parabolicreflector 922-B projects light pattern 836-B at a second angle).

In some embodiments, the first parabolic reflector has a first surfaceprofile and the second parabolic reflector has a second surface profiledistinct from the first surface profile (e.g., in FIG. 9I, parabolicreflector 922-C has a surface profile that is distinct from surfaceprofile 922-A).

In some embodiments, the system includes a plurality of attenuatorsoptically coupled with the plurality of parabolic reflectors andconfigured to attenuate intensity of light provided by respectiveparabolic reflectors of the plurality of parabolic reflectors (e.g.,parabolic reflectors 922-A and 922-B in FIG. 9H are optically coupledwith attenuators 904-A and 904-B shown in FIG. 9A).

In some embodiments, the plurality of attenuators includes a firstattenuator (e.g., attenuator 904-A in FIG. 9A) optically coupled with afirst parabolic reflector of the plurality of parabolic reflectors(e.g., parabolic reflector 922-A) and configured to attenuate intensityof light provided by the first parabolic reflector (e.g., light pattern836-A) by a first attenuation factor (e.g., 10% or zero attenuation) anda second attenuator (e.g., attenuator 904-B in FIG. 9A) opticallycoupled with a second parabolic reflector (e.g., parabolic reflector922-B), that is distinct from the first parabolic reflector, of theplurality of parabolic reflectors and configured to attenuate intensityof light provided by the second parabolic reflector (e.g., light pattern836-B) by a second attenuation factor (e.g., 20% attenuation) that isdistinct from the first attenuation factor.

In some embodiments, the system includes one or more lenses coupled withthe plurality of parabolic reflectors (e.g., lenses 924 in FIG. 9I). Insome embodiments, lenses 924 are arranged in a microlens array. In someembodiments, lenses 924 are replaced by a single condenser lens (e.g.,lens 936 in FIG. 9K).

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source, and separating thelight into a first portion of the light and a second portion of thelight that is spatially separated from the first portion of the light(e.g., FIG. 8A). The method also includes transmitting the first portionof the light through a first set of optical elements to provide a firstwide-field beam (e.g., FIG. 8A), transmitting the second portion of thelight through a second set of optical elements to provide a secondwide-field beam that is spatially separated from the first wide-fieldbeam onto an optically recordable medium (e.g., FIG. 8A), and reflectingthe second wide-field beam with a plurality of parabolic reflectors toprovide a plurality of separate light patterns (e.g., reflectingwide-field beam 836-A with parabolic reflectors 922 as light patterns836 as shown in FIG. 9H). The method further includes concurrentlyprojecting the first wide-field beam and reflecting the plurality ofseparate light patterns onto the optically recordable medium to form theholographic medium (e.g., projecting wide-field beam 832-B and lightpatterns 836 concurrently onto optically recordable medium 826 in FIG.9H).

In some embodiments, the plurality of parabolic reflectors is arrangedin a circular configuration (e.g., FIG. 9C).

In some embodiments, the method includes projecting the plurality ofseparate light patterns arranged in a circular configuration (e.g.,parabolic reflectors 922 in FIG. 9H are arranged in a circularconfiguration illustrated in FIG. 9C for projecting light patternsarranged in a circular configuration).

In some embodiments, the plurality of parabolic reflectors is arrangedin a rectangular configuration (e.g., FIG. 9B).

In some embodiments, the method includes projecting the plurality ofseparate light patterns arranged in a rectangular configuration (e.g.,parabolic reflectors 922 in FIG. 9H are arranged in a rectangularconfiguration for projecting light patterns arranged in a rectangularconfiguration illustrated in FIG. 9B).

In some embodiments, the method includes focusing the second wide-fieldbeam onto a focal plane that is adjacent to the optically recordablemedium (e.g., FIG. 9H).

In some embodiments, the method includes focusing, with each parabolicreflector of the plurality of parabolic reflectors, a respective portionof the second wide-field beam on a reference focal plane, the referencefocal plane located between the optically recordable medium and areference pupil. For example, the reference focal plane is locatedbetween the holographic medium and an eye of a user of an eye tracker(e.g., reference plane 902 corresponds to reference plane 410-1 FIG.4A).

In some embodiments, the method includes projecting, with a firstparabolic reflector of the plurality of parabolic reflectors, a firstlight pattern of the plurality of separate light patterns onto theoptically recordable medium at a first angle, and projecting, with asecond parabolic reflector of the plurality of parabolic reflectors, asecond light pattern of the plurality of separate light patterns ontothe optically recordable medium at a second angle that is distinct fromthe first angle (e.g., FIG. 9H). For example, the first angle is 45degrees with respect to an optical axis of the holographic medium (e.g.,an optical axis that is perpendicular to the holographic medium), andthe second angle is 20 degrees with respect to the optical axis of theholographic medium.

In some embodiments, the method includes attenuating, with a firstattenuator optically coupled with a parabolic reflector of the pluralityof parabolic reflectors, intensity of light provided to the firstparabolic reflectors by a first attenuation factor (e.g., 10% or noattenuation) and attenuating, with a second attenuator optically coupledwith a second parabolic reflector, that is distinct from the firstparabolic reflector, of the plurality of parabolic reflectors, intensityof light provided to the second parabolic reflectors by a secondattenuation factor (e.g., 20% attenuation) that is distinct from thefirst attenuation factor (e.g., attenuators 904-A and 904-B in FIG. 9Aoptically coupled with parabolic reflectors 836-A and 836-B in FIG. 9H).

In accordance with some embodiments, a holographic medium is made by themethod described herein (e.g., holographic medium 404 in FIG. 4A).

In accordance with some embodiments, a system for making a holographicmedium includes a light source configured to provide light and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light (e.g., FIG. 8A). The system also includesa first set of optical elements configured to transmit the first portionof the light for providing a first wide-field beam onto an opticallyrecordable medium (e.g., FIG. 8A) and one or more diffractive opticalelements configured to receive the second portion of the light andproject a plurality of separate light patterns onto the opticallyrecordable medium for forming the holographic medium (e.g., in FIG. 9K,DOE 934 receives beam 834-D and projects it as light patterns, such aslight patterns 932-A and 932-B, onto optically recordable medium 826).

In some embodiments, the light provided by the light source is coherentlight (e.g., light source 802 provides coherent light in FIG. 8A).

In some embodiments, the one or more diffractive optical elements areconfigured to project a first light pattern (e.g., light pattern 932-Ain FIG. 9K) of the plurality of separate light patterns onto theoptically recordable medium at a first angle (e.g., 15 degrees), andproject a second light pattern (e.g., light pattern 932-B) of theplurality of separate light patterns onto the optically recordablemedium at a second angle (e.g., 0 degrees) that is distinct from thefirst angle.

In some embodiments, the one or more diffractive optical elements areoptically coupled with one or more lenses configured to focus light fromthe one or more diffractive optical elements (e.g., in FIG. 9K, DOE 934is coupled with lens 936).

In some embodiments, the one or more lenses are configured to focus thelight from the one or more diffractive optical elements on a referencefocal plane located between the optically recordable medium and areference pupil.

In some embodiments, the one or more diffractive optical elementsinclude one or more diffractive beam splitters configured to project anarray of spots (e.g., DOE 934 in FIG. 9K includes one or morediffractive beam splitters forming a plurality of light patterns shownin FIG. 9B).

In some embodiments, the one or more diffractive optical elementsinclude one or more diffractive diffusers (e.g., DOE 934 in FIG. 9Kincludes one or more diffractive diffusers).

In some embodiments, the one or more diffractive optical elements (e.g.,DOE 934 in FIG. 9K) are optically coupled with a plurality of lenses(e.g., lens 936 in FIG. 9A is replaced with lenses 820-1 in FIG. 9A), afirst lens of the plurality of lenses configured to focus a firstportion of light from the one or more diffractive optical elements(e.g., light pattern 932-A) and a second lens of the plurality of lensesconfigured to focus a second portion (e.g., light pattern 932-B),distinct from the first portion, of light from the one or morediffractive optical elements.

In some embodiments, the plurality of lenses is arranged in a microlensarray (e.g., lenses 820-1 in FIG. 9A are arranged in a microlens array).

In some embodiments, the system includes one or more diffusersconfigured to diffuse light from the one or more diffractive opticalelements (e.g., diffuser 938 diffuses light patterns 932-A and 932-B inFIG. 9K).

In some embodiments, the plurality of separate light patterns isarranged in a circular configuration (e.g., DOE 934 projects lightpatterns, such as light patterns 932-A and 932-B, in a circularconfiguration).

In some embodiments, the plurality of separate light patterns isarranged in a rectangular configuration (e.g., DOE 934 projects lightpatterns, such as light patterns 932-A and 932-B, in a rectangularconfiguration).

In some embodiments, the system includes a second set of opticalelements configured to direct the second portion of the light toward theone or more diffractive optical elements (e.g., the second set ofoptical elements 800-B in FIG. 8A directs beam 834-D in FIG. 9K towardDOE 934).

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source and separating thelight into a first portion of the light and a second portion of thelight that is spatially separated from the first portion of the light(e.g., FIG. 8A). The method also includes transmitting the first portionof the light through a first set of optical elements to provide a firstwide-field beam (e.g., FIG. 8A), transmitting the second portion of thelight through one or more diffractive optical elements to provide aplurality of separate light patterns (e.g., FIG. 9K), and concurrentlyprojecting the first wide-field beam and the plurality of separate lightpatterns onto the optically recordable medium to form the holographicmedium (e.g., FIG. 8A).

In some embodiments, the method includes focusing, with one or morelenses, light from the one or more diffractive optical elements (e.g.,FIG. 9K).

In some embodiments, the light from the one or more diffractive opticalelements is focused by the one or more lenses onto a reference focalplane located between the optically recordable medium and a referencepupil.

In some embodiments, the method includes projecting the one or morediffractive optical elements, a first light pattern of the plurality ofseparate light patterns onto the optically recordable medium at a firstangle, and projecting, with the one or more diffractive opticalelements, a second light pattern of the plurality of separate lightpatterns onto the optically recordable medium at a second angle that isdistinct from the first angle (e.g. FIG. 9K).

In some embodiments, the method includes directing, with a second set ofoptical elements, the second portion of the light toward the one or morediffractive optical elements (e.g., FIG. 8A).

In some embodiments, the method includes diffusing, with one or morediffusers, light from the one or more diffractive optical elements(e.g., FIG. 9K).

In accordance with some embodiments, a holographic medium is made by themethod described herein (e.g., holographic medium 404 in FIG. 4A).

In accordance with some embodiments, a system for making a holographicmedium, includes a light source configured to provide light and a beamsplitter configured to separate the light into a first portion of thelight and a second portion of the light that is spatially separated fromthe first portion of the light (e.g., FIG. 8A). The system also includesa first set of optical elements configured to transmit the first portionof the light for providing a first wide-field beam onto an opticallyrecordable medium (e.g., FIG. 8A) and a plurality of optical fibersconfigured to receive the second portion of the light and project aplurality of separate light patterns onto the optically recordablemedium for forming the holographic medium (e.g., optical fibers 944receive beam 834-A and project light patterns 942 onto opticallyrecordable medium 826 in FIG. 9L).

In some embodiments, the light provided by the light source is coherentlight (e.g., light source 802 provides coherent light in FIG. 8A).

In some embodiments, each optical fiber of the plurality of opticalfibers includes a first optical fiber end optically coupled with thelight source (e.g., input fiber end 948-1 in FIG. 9L) and a secondoptical fiber end (e.g., output fiber end 948-2), opposite to the firstoptical fiber end, configured to provide a respective light pattern ofthe plurality of separate light patterns (e.g., light patterns 942). Insome embodiments, the optical fibers are single-mode fibers. In someembodiments, the plurality of optical fibers is optically coupled withthe light source by a single fiber (e.g., optical fiber 946). Forexample, a single optical fiber is split into a plurality of opticalfibers 944.

In some embodiments, respective second optical fiber ends of theplurality of optical fibers are arranged in a circular configuration(e.g., respective output fiber ends 948-2 of optical fibers 942 arearranged in a circular configuration illustrated in FIG. 9C).

In some embodiments, respective second optical fiber ends of theplurality of optical fibers are arranged in a rectangular configuration(e.g., respective output ends 948-2 of optical fibers 942 are arrangedin a rectangular configuration illustrated in FIG. 9B).

In some embodiments, respective second fiber ends of the plurality ofoptical fibers are positioned adjacent to the optically recordablemedium (e.g., output fiber ends 948-2 are positioned adjacent tooptically recordable medium 826 in FIG. 9L).

In some embodiments, the plurality of optical fibers includes a firstoptical fiber configured to project a first light pattern of theplurality of separate light patterns onto the optically recordablemedium at a first angle (e.g., optical fiber 944-A projects lightpattern 942-A onto optically recordable medium 826 at a first angle inFIG. 9L, such as 30 degrees), and a second optical fiber configured toproject a second light pattern of the plurality of separate lightpatterns onto the optically recordable medium at a second angle that isdistinct from the first angle (e.g., optical fiber 944-B projects lightpattern 942-B onto optically recordable medium 826 at a second angle,such as 20 degrees).

In some embodiments, the plurality of optical fibers is coupled with aplurality of lenses (e.g., lenses 950 in FIG. 9L).

In some embodiments, the plurality of lenses is arranged in a microlensarray (e.g., lenses 950 are arranged in a microlens array).

In some embodiments, each lens of the plurality of lenses is configuredto focus a respective light pattern of the plurality of separate lightpatterns on a reference focal plane, the reference focal plane locatedbetween the optically recordable medium and a reference pupil.

In some embodiments, the plurality of optical fibers is coupled with acondenser lens (e.g., lenses 950 in FIG. 9L are replaced with a singlecondenser lens, such as lens 936 in FIG. 9K, or a condenser lens is usedin conjunction with lenses 950). In some embodiments, the condenser lensis configured to focus the plurality of separate light patterns on areference focal plane, the reference focal plane located between theoptically recordable medium and a reference pupil.

In some embodiments, the system includes a second set of opticalelements configured to couple the second portion of the light into theplurality of optical fibers (e.g., the second set of optical elements800-B in FIG. 8A couples beam 834-A to optical fibers 944 in FIG. 9K).

In some embodiments, the system includes a plurality of optical filters(e.g., filters 952 in FIG. 9L) optically coupled with the plurality ofoptical fibers and configured to modify a color of the light provided byrespective optical fibers of the plurality of optical fibers.

In some embodiments, the system includes a plurality of attenuatorsoptically coupled with the plurality of optical fibers and configured toattenuate intensity of light provided by respective optical fibers ofthe plurality of optical fibers (e.g., attenuators 904-A and 904-B inFIG. 9A are coupled with respective optical fibers 944-A and 944-B inFIG. 9B).

In accordance with some embodiments, a method for making a holographicmedium includes providing light from a light source and separating thelight into a first portion of the light and a second portion of thelight that is spatially separated from the first portion of the light(e.g., FIG. 8A). The method also includes transmitting the first portionof the light through a first set of optical elements to provide a firstwide-field beam (e.g., FIG. 8A), transmitting the second portion of thelight through a plurality of optical fibers to provide a plurality ofseparate light patterns (e.g., FIG. 9L), and concurrently projecting thefirst wide-field beam and the plurality of separate light patterns ontothe optically recordable medium to form the holographic medium (e.g.,FIG. 8A).

In some embodiments, the method includes projecting the plurality ofseparate light patterns arranged in a circular configuration (e.g.,optical fibers 944 project light patterns 942 in FIG. 9L in a circularconfiguration).

In some embodiments, the method includes projecting the plurality ofseparate light patterns arranged in a rectangular configuration (e.g.,optical fibers 944 project light patterns 942 in FIG. 9L in arectangular configuration).

In some embodiments, the method includes focusing, with a plurality oflenses coupled with the plurality of optical fibers, the plurality ofseparate light patterns onto a focal plane that is adjacent to theoptically recordable medium (e.g., lenses 950 focus light patterns 924-Aand 942-B in FIG. 9A on a reference plane, such as reference plane 902in FIG. 9A).

In some embodiments, the plurality of lenses is arranged in a microlensarray (e.g., lenses 950 in FIG. 9A).

In some embodiments, the method includes focusing, with a condenser lenscoupled with the plurality of optical fibers (e.g., lens 936 in FIG. 9Kis coupled with optical fibers 944 in FIG. 9L), the plurality ofseparate light patterns onto a focal plane that is adjacent to theoptically recordable medium (e.g., light patterns 924 in FIG. 9L arefocused on a reference plane, such as reference plane 902 in FIG. 9A).

In some embodiments, the method includes projecting, with a firstoptical fiber of the plurality of optical fibers, a first light patternof the plurality of separate light patterns onto the opticallyrecordable medium at a first angle, and projecting, with a secondoptical fiber of the plurality of optical fibers, a second light patternof the plurality of separate light patterns onto the opticallyrecordable medium at a second angle that is distinct from the firstangle (e.g., FIG. 9L).

In accordance with some embodiments, a holographic medium is made by themethod described herein (e.g., holographic medium 404 in FIG. 4A).

Although various drawings illustrate operations of particular componentsor particular groups of components with respect to one eye, a personhaving ordinary skill in the art would understand that analogousoperations can be performed with respect to the other eye or both eyes.For brevity, such details are not repeated herein.

Although some of various drawings illustrate a number of logical stagesin a particular order, stages which are not order dependent may bereordered and other stages may be combined or broken out. While somereordering or other groupings are specifically mentioned, others will beapparent to those of ordinary skill in the art, so the ordering andgroupings presented herein are not an exhaustive list of alternatives.Moreover, it should be recognized that the stages could be implementedin hardware, firmware, software or any combination thereof.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit the scope of the claims to the precise forms disclosed. Manymodifications and variations are possible in view of the aboveteachings. The embodiments were chosen in order to best explain theprinciples underlying the claims and their practical applications, tothereby enable others skilled in the art to best use the embodimentswith various modifications as are suited to the particular usescontemplated.

What is claimed is:
 1. A system for making a holographic medium for usein generating light patterns for eye tracking, the system including: alight source configured to provide light; a beam splitter configured toseparate the light into a first portion of the light and a secondportion of the light that is spatially separated from the first portionof the light; a first set of optical elements configured to transmit thefirst portion of the light for providing a first wide-field beam onto anoptically recordable medium; and one or more diffractive opticalelements configured to receive the second portion of the light andproject a plurality of separate light patterns onto the opticallyrecordable medium for forming the holographic medium.
 2. The system ofclaim 1, wherein the light provided by the light source is coherentlight.
 3. The system of claim 1, wherein the one or more diffractiveoptical elements are configured to project a first light pattern of theplurality of separate light patterns onto the optically recordablemedium at a first angle, and project a second light pattern of theplurality of separate light patterns onto the optically recordablemedium at a second angle that is distinct from the first angle.
 4. Thesystem of claim 1, wherein the one or more diffractive optical elementsare optically coupled with one or more lenses configured to focus lightfrom the one or more diffractive optical elements.
 5. The system ofclaim 4, wherein the one or more lenses are configured to focus thelight from the one or more diffractive optical elements on a referencefocal plane located between the optically recordable medium and areference pupil.
 6. The system of claim 1, wherein the one or morediffractive optical elements include one or more diffractive beamsplitters configured to project an array of spots.
 7. The system ofclaim 1, wherein the one or more diffractive optical elements includeone or more diffractive diffusers.
 8. The system of claim 1, wherein theone or more diffractive optical elements are optically coupled with aplurality of lenses, a first lens of the plurality of lenses configuredto focus a first portion of light from the one or more diffractiveoptical elements and a second lens of the plurality of lenses configuredto focus a second portion, distinct from the first portion, of lightfrom the one or more diffractive optical elements.
 9. The system ofclaim 8, wherein the plurality of lenses is arranged in a microlensarray.
 10. The system of claim 1, including one or more diffusersconfigured to diffuse light from the one or more diffractive opticalelements.
 11. The system of claim 1, wherein the plurality of separatelight patterns is arranged in a circular configuration.
 12. The systemof claim 1, wherein the plurality of separate light patterns is arrangedin a rectangular configuration.
 13. The system of claim 1, including asecond set of optical elements configured to direct the second portionof the light toward the one or more diffractive optical elements.
 14. Amethod for making a holographic medium for use in generating lightpatterns for eye tracking, the method including: providing light from alight source; separating the light into a first portion of the light anda second portion of the light that is spatially separated from the firstportion of the light; transmitting the first portion of the lightthrough a first set of optical elements to provide a first wide-fieldbeam; transmitting the second portion of the light through one or morediffractive optical elements to provide a plurality of separate lightpatterns; and concurrently projecting the first wide-field beam and theplurality of separate light patterns onto an optically recordable mediumto form the holographic medium.
 15. The method of claim 14, includingfocusing, with one or more lenses, light from the one or morediffractive optical elements.
 16. The method of claim 15, wherein thelight from the one or more diffractive optical elements is focused bythe one or more lenses onto a reference focal plane located between theoptically recordable medium and a reference pupil.
 17. The method ofclaim 14, including projecting the one or more diffractive opticalelements, a first light pattern of the plurality of separate lightpatterns onto the optically recordable medium at a first angle, andprojecting, with the one or more diffractive optical elements, a secondlight pattern of the plurality of separate light patterns onto theoptically recordable medium at a second angle that is distinct from thefirst angle.
 18. The method of claim 14, including directing, with asecond set of optical elements, the second portion of the light towardthe one or more diffractive optical elements.
 19. The method of claim14, including diffusing, with one or more diffusers, light from the oneor more diffractive optical elements.
 20. A holographic medium made bythe method of claim 14 for use in generating light patterns for eyetracking.